... skinGrid? ...

`. But currently skinGrid is in startScreen. Need reuse or duplicate? Could move skinGrid out of startScreen to shop modal, and shop modal includes it. But startScreen also should show skin selection? User wants shop button opens purchase skins and switch main character. The start screen already had skin grid. They want \"first screen can select different skins, but need money unlock; money floats in sky...\" That was previous. Now add shop button top-left to open purchase skin screen. So maybe start screen no longer shows grid? But they didn't say remove. They say start screen has start button (previous) and slider. Add shop button top-left. Could keep skin grid in startScreen and also have shop? But might clutter. Better: Move skinGrid from startScreen into a shop overlay; startScreen shows title, coin display, start button; shop button opens overlay with skin grid. But previous prompt said first screen can choose skins. Now shop button does that. The first screen could still show skin selection? User didn't explicitly remove. They want \"畫面左上角加入商店按鈕可以開啟購買皮膚的畫面並給玩家隨時轉換主角皮膚再次按下商店按鈕可以繼續遊戲\". So shop button should open skin purchase screen. Could repurpose existing skinGrid by moving to shopScreen. Then startScreen no longer contains skinGrid. But user may want first screen still has skin selection? The current screen already had. The new instruction may override: shop button handles skins. We can keep a small preview of selected skin on startScreen? Maybe optional. But to avoid clutter, remove grid from start and put in shop. But then if they expect first screen choose skin, they can press shop. Good.\n\nNeed ensure shop button visible on start screen and during game. Use same button top-left.\n\nShop overlay content: title \"商店\", coin display, skinGrid (moved), hint, close/resume button \"繼續遊戲\". When opened, pause game if playing. When closed, resume if was playing.\n\n2. style.css: Add shop button styling. Resize volumePanel: maybe width auto ~55% bottom-left. Make fonts smaller. Add shop screen styling (similar overlay). Make skin grid maybe 2 columns etc. Ensure start button not covered. Since volumePanel bottom-left, start button central. Add .icon-btn top-left.\n\n3. game.js:\n- Add DOM refs: shopBtn, shopScreen, closeShopBtn, maybe shopTitle/hint/coin display inside shop. Use existing skinGrid? We'll move skinGrid element to shopScreen; update references.\n- Shop button toggles shop. Need track `isShopOpen` and previous gameState maybe `gameStateBeforeShop`. When open: set isShopOpen true; if gameState==='playing', set gameState='paused' and gameStateBeforeShop='playing'; else gameStateBeforeShop = gameState; show shop overlay; hide hud? Keep? Maybe hide hud and volume panel? volumePanel can stay? Better hide game overlays while shop open? Not necessary but simpler. The shop overlay is z-index high; keep hud visible maybe. But shop button top-left visible.\n- When close: hide shop; if gameStateBeforeShop==='playing', set gameState='playing'; else maybe start/gameover. If game over and shop closed? Could just keep gameover. But \"再次按下商店按鈕可以繼續遊戲\" implies during gameplay. So close resumes if was playing.\n- More floating coins: reduce COIN_SPAWN_RATE, maybe 70; add bag spawn rate. Add bag of coins image asset. Define COIN_BAG_VALUE=10, COIN_BAG_SPAWN_RATE=400. spawnCoin() can accept type/value. Use coin.type and coin.value, coin.radius maybe larger for bag. Draw accordingly.\n- Need load bagImg. Add `const bagImg = new Image(); bagImg.src='coin_bag.png';`\n- spawnCoin logic: randomly decide bag with probability 0.15 when spawn interval. Or use separate rate. Let's do if frames % COIN_BAG_SPAWN_RATE === 0 and Math.random()<0.6 spawn bag. Otherwise if frames % COIN_SPAWN_RATE ===0 spawn coin cluster of 1-3 coins. Need ensure not too many collisions. Simpler: every COIN_SPAWN_RATE frames, spawn 1-3 regular coins in a small arc; and occasionally bag.\n- Need updateCoins handle value and image draw. For bag, radius 22, drawImage bagImg.\n- Ensure bag gives 10 coins.\n- The coin display start: already in startScreen. Shop overlay also maybe coin count. We'll create span id coinCountShop.\n\nNeed generate coin_bag.png asset. We can output asset creation block. Also maybe generate no audio. Use description: \"A pixel art bag of gold coins tied at the top, glowing with sparkles, game treasure item, simple cartoon style\". transparent true aspect square.\n\nNeed consider mobile: one screen height, no scrolling. Shop skin grid max-height should fit within overlay without pushing start button? Since shop modal overlay full screen, can scroll grid. The user didn't ask to avoid scrolling in shop. Fine.\n\nNeed adjust start screen layout: remove skinGrid and skinHint? Keep maybe hint \"按下商店按鈕選擇與購買主角\". But instruction no. Maybe keep minimal.\n\nLet's design final index.html:\n\n```\n

\n\n \n \n\n \n

聽話鳥

\n $\"金幣\"$ 0\n

用聲音控制小鳥飛行

\n \n

\n\n \n

商店

\n $\"金幣\"$ 0\n

選擇已擁有的皮膚，或花金幣解鎖

\n \n

\n\n \n ...\n```\n\nVolumePanel remains bottom.\n\nCSS changes:\n- Add .shop-btn position absolute top 12px left 12px z-index 20.\n- .icon-btn styling 48x48 etc.\n- #volumePanel reduce width maybe 58%, bottom 12 left 12, padding 10 12, font smaller.\n- thresholdSlider height 36px.\n- #volumeMeter height 16px.\n- Ensure no overlap with shop btn? Different corners.\n\nJS changes:\n- Remove references to skinHint? It's still used.\n- Add shopScreen, shopBtn, closeShopBtn, coinCountShop.\n- Toggle shop function.\n- startBtn listener still startGame.\n- Need renderSkinGrid now inside shop. It uses coinCountStart? It calls updateCoinDisplays which updates coinCount, coinCountStart. Add shop count.\n- updateCoinDisplays updates three spans.\n- In handleSkinClick update coin displays.\n- Game loop: update only if gameState==='playing'.\n- Need handle shop open pause/resume. `let wasPlaying = false;` When open: if gameState==='playing' { gameState='paused'; wasPlaying=true; } show shop, renderSkinGrid maybe. When close: hide shop; if wasPlaying gameState='playing'; else if gameState==='start' maybe leave start; etc.\n- Need shop button visible during game over? Maybe yes; but opening shop from gameover then close should resume? They said again press to continue game; maybe only during game. We can make close resume only if wasPlaying.\n\nCoin bag:\n- Add asset coin_bag.png. Need load.\n- Constants:\n```\nconst COIN_SPAWN_RATE = 80;\nconst COIN_BAG_SPAWN_RATE = 320;\nconst COIN_VALUE = 1;\nconst COIN_BAG_VALUE = 10;\n```\n- spawnCoin function perhaps `function spawnCoin(type='coin')` choose random y. For bag radius 24. For regular cluster: radius 16.\n- updateCoins: separate loops. For each coin: check distance. Add coin.value.\n- drawCoins: draw appropriate image. If bagImg complete draw bagImg with radius*2. If regular coinImg.\n\nBut we also need to make floating coins more numerous. Use cluster:\n```\nif (frames % COIN_SPAWN_RATE === 0) {\n const count = Math.floor(Math.random()*3)+1; // 1-3\n const baseY = random...\n for(let i=0;i` to before startScreen. Add button.\n\nBlock 2: Replace startScreen content to remove skinGrid/skinHint.\nSearch entire startScreen div block. Replace with simpler version.\n\nBlock 3: Add shopScreen overlay before gameOverScreen.\nSearch `` and insert before.\n\nBlock 4: Remove skinHint? We'll keep but move to shop.\n\nNo more.\n\nCSS changes:\nBlock A: Add icon-btn and shop-btn styles. Search `#gameCanvas` block? Insert after #gameCanvas maybe.\nBlock B: Modify #volumePanel styles (width, bottom, left, right, padding). Search existing #volumePanel block replace with smaller.\nBlock C: Maybe adjust .skin-grid max-height in shop. Search `#skinGrid` styles, maybe modify max-height to 45vh.\nBlock D: Ensure overlay h1/h2? Fine.\n\nJS changes:\nBlock 1: Add DOM refs after existing ones: shopBtn, shopScreen, closeShopBtn, coinCountShop.\nBlock 2: Add constants COIN_BAG.\nBlock 3: Add bagImg load.\nBlock 4: Modify updateCoinDisplays to include coinCountShop.\nBlock 5: Modify renderSkinGrid maybe no change; it calls updateCoinDisplays.\nBlock 6: Add toggleShop, openShop, closeShop functions. Place after updateHearts maybe.\nBlock 7: Modify startGame to hide shop maybe and reset wasPlaying.\nBlock 8: Add event listeners for shopBtn and closeShopBtn.\nBlock 9: Modify updateCoins to spawn clusters and bag and handle types.\nBlock 10: Modify drawCoins to draw bag.\nBlock 11: Add isMobile and hide heal button.\n\nNeed be careful with exact text uniqueness.\n\nLet's write detailed changes.\n\nFirst, create asset.\n\ncoin_bag.png\n```\ndescription: \"A pixel art treasure bag full of gold coins tied at the top with a gold string, glowing sparkles around it, game item, simple cartoon style\"\ntransparent: true\naspect: square\n```\n\nNow index.html edits.\n\nEdit 1: Add shop button.\nSearch:\n```\n

\n \n \n```\nReplace:\n```\n

\n \n \n \n \n \n```\n\nEdit 2: Replace startScreen.\nSearch:\n```\n \n

聽話鳥

\n $\"金幣\"$ \n 0\n

選擇主角後開始遊戲

\n \n

\n```\nReplace:\n```\n \n

聽話鳥

\n $\"金幣\"$ \n 0\n \n\nThe user wants me to make corrections to their existing game code. Let me analyze what needs to be changed:\n\n1. Make the volume threshold slider smaller and move it to bottom-left to avoid covering the start button\n2. Add a shop button at top-left that opens a skin purchase screen, allowing players to switch skins anytime. Press again to continue game\n3. Add more floating coins in the sky\n4. Add a bag of coins floating in sky worth 10 coins (need to add a coin_bag.png asset)\n\nLet me plan the changes:\n\n### 1. Volume Panel changes\n- Move to bottom-left\n- Make it smaller (maybe width ~45%)\n- Reduce padding/font sizes\n- Avoid covering start button\n\n### 2. Shop button\n- Add shop button at top-left\n- Create shop overlay/modal showing skin grid\n- When in game, pause game while shop is open\n- Shop button toggles the shop\n- Allow selecting owned skins, purchasing locked skins\n- Resume game when closed\n\nNeed to restructure the skin selection logic. Currently the start screen shows skin grid. I need to also add a shop overlay with skin grid.\n\n### 3. More floating coins\n- Reduce COIN_SPAWN_RATE or spawn multiple coins at once\n- Maybe spawn coins in clusters\n\n### 4. Coin bag worth 10 coins\n- Need to create coin_bag.png asset\n- Add to floating items array, distinguish coin vs bag\n- Bag gives 10 coins\n\nLet me also check the game structure. The skin grid is currently shown in start screen. The user wants a shop button at top-left that opens shop. I should:\n- Keep start screen simple with just title, coin display, start button\n- Add shop button in HUD (top-left or similar) that opens shop overlay\n- The shop overlay contains the skin grid\n\nWait, the prompt says \"畫面左上角加入商店按鈕\" - add shop button at top-left. So on game screen (HUD) add shop button. But also the start screen maybe should have it? The prompt says \"可以開啟購買皮膚的畫面並給玩家隨時轉換主角皮膚再次按下商店按鈕可以繼續遊戲\" - can open skin purchase screen anytime and switch skins, press again to continue game. So this is mainly during gameplay. But it makes sense to have it accessible from start screen too.\n\nActually, re-reading: \"畫面左上角加入商店按鈕可以開啟購買皮膚的畫面並給玩家隨時轉換主角皮膚再次按下商店按鈕可以繼續遊戲\". So during game, top-left has shop button. Open shop, select/change skin, press again to continue.\n\nLet me structure:\n- Keep skin grid in start screen? Or move to shop? The user said to add shop button, so I'll move skin grid to a shop overlay that's accessible from both start screen and game HUD. But to keep things simple and not break existing flow, I can:\n - Add a shop button in HUD (top-left)\n - Create shop overlay that contains skin grid\n - On start screen, maybe keep the skin grid there too, or replace with shop button. The prompt says \"靈敏度...放到畫面左下角避免遮蓋開始按鈕\" - this implies the start button is still there. So I'll keep start screen with title, coin, start button, and volume panel at bottom-left small.\n - But skin grid currently takes up space in start screen. The user didn't explicitly say to remove it from start screen, but they want a shop button. Hmm. Actually, with shop button, maybe the skin grid should be in the shop overlay. But the previous prompt was about selecting skin before starting. Let me keep skin selection in start screen for now, and also add shop button accessible during game. Actually, that would be redundant. Let me think...\n\nActually the most sensible interpretation: They want a dedicated shop interface. The start screen can have a shop button instead of showing all skins. But to minimize changes and not confuse, I'll:\n- Keep the start screen simple: title, coin display, start button\n- Add a \"商店\" button on start screen (top area or near start button)\n- Add a \"商店\" button in HUD at top-left during gameplay\n- Create a shop overlay with the skin grid\n- In shop, can select/buy skins\n- Press shop button again (or close button) to close shop and continue game\n\nActually the prompt specifically says \"畫面左上角加入商店按鈕\". On mobile in iframe, top-left is a good spot. But during start screen, top-left could also have it. Let me add it to HUD and make it visible during both start and playing? That might be complex.\n\nSimpler approach:\n- Add shop button to start screen (top-left area or as a small button)\n- Add shop button to HUD (top-left), visible during playing and gameover? Maybe only during playing.\n- Shop overlay can be opened from both\n- When shop is open, game is paused if it was playing\n\nLet me reconsider the layout. For mobile, the HUD currently has score top-left and hearts top-right. I can add shop button next to score or make score smaller. Or put shop button at top-left, score below it.\n\nFor start screen, I can add a small shop button at top-left corner.\n\n### Changes needed:\n\n#### index.html\n- Move volumePanel outside overlay or keep it but style differently\n- Add shop button\n- Add shop overlay\n- Remove skin grid from start screen (or keep?)\n\nLet me decide: I'll move skin grid to a dedicated shop overlay, and add shop buttons to start screen and HUD.\n\nActually, looking at current code, the start screen has skinGrid inside it. If I move it to shop overlay, I need to remove from startScreen and create shopScreen overlay.\n\n#### style.css\n- Resize volume panel to bottom-left, smaller\n- Style shop button\n- Style shop overlay\n- Make start screen simpler\n\n#### game.js\n- Add shop screen handling\n- Move skin grid rendering to shop screen\n- Add coin bag asset and logic\n- Increase coin spawn frequency/quantity\n- Handle shop button toggling and game pause/resume\n\nLet me write the code.\n\nFor the coin bag asset, I need to generate:\ncoin_bag.png\ndescription: \"A pixel art brown sack overflowing with shiny gold coins, tied at the top, game treasure item, simple cartoon style\"\ntransparent: true\naspect: square\n\nLet me also think about the shop button placement and state management.\n\nGame states: 'start', 'playing', 'paused' (shop open), 'gameover'\n\nWhen shop is opened during playing, set state to 'paused'. When closed, set back to 'playing'.\nWhen shop is opened during start, game is not started, so no need to pause.\n\nLet me implement a toggleShop function.\n\nShop button: visible on start screen (top-left) and during playing (in HUD). On game over, maybe hidden or could show. Let's keep it visible during gameover too? The user said \"隨時轉換主角皮膚\" - anytime. But gameover has the heal button. Maybe keep shop available on gameover too. But to keep simple, I'll show it in start and playing. Actually if gameover and player uses heal, they continue. If they want to switch skin during gameover before healing? Maybe not necessary. I'll hide it on gameover to keep focus.\n\nActually the user wants \"隨時\" - anytime. Let me add it to HUD and show it always except maybe when shop is open. But during gameover, the HUD is hidden currently. Hmm. Let me not overcomplicate - add shop button to HUD, and HUD is visible during start? Currently HUD is hidden during start. Let me make shop button visible on start screen separately.\n\nLayout plan:\n- Start screen: title, coin display, start button. Volume panel at bottom-left. Shop button at top-left of screen (outside overlay or as absolute positioned element).\n- During game: HUD with score/coins top-left, hearts top-right. Shop button at top-left next to or below score. Volume panel at bottom-left.\n- Shop overlay: full screen, shows skin grid, close button, title \"商店\".\n\nActually for start screen, having shop button at top-left absolute position (z-index above overlay) makes sense.\n\nFor gameplay HUD, I can put shop button at top-left, then score/coins to its right or below.\n\nLet me design:\n- #shopBtn absolute top: 12px; left: 12px; z-index: 20\n- During start, visible\n- During playing, also visible\n- During gameover, maybe hidden\n\nBut if it's always at top-left, it might overlap with HUD score. Let me make it small and place it, then in HUD put score next to it.\n\nMaybe better:\n- Have two shop buttons? One for start screen, one for HUD. But that's redundant.\n- Or use one #shopBtn that stays visible, styled appropriately.\n\nLet me use one #shopBtn fixed at top-left. During start screen, it's visible. During game, visible. The HUD elements need to account for it by shifting right.\n\nFor simplicity:\n- Shop button: top: 10px; left: 10px; width: 44px; height: 44px; border-radius: 50%;\n- Score/coin in HUD: margin-left: 56px (to the right of shop button)\n\nActually on start screen, the overlay covers everything. If shop button is outside overlay (higher z-index), it will be visible. Good.\n\nLet me create:\n```html\n\n```\n\nAnd a shop overlay:\n```html\n

商店

\n $\"金幣\"$ \n 0\n

\n \n

\n```\n\nAnd remove skinGrid from startScreen.\n\nIn game.js:\n- Add shopBtn, shopScreen, closeShopBtn, coinCountShop\n- renderSkinGrid now renders to shop screen\n- handleSkinClick updates selected skin and birdImg immediately\n- toggleShop: if hidden, show shop, pause game if playing. If visible, hide shop, resume playing or go to start.\n- shopBtn event listener\n\nFor the volume panel on start screen: The prompt says \"靈敏度/門檻調節滑桿列表按比例縮細並放到畫面左下角避免遮蓋開始按鈕\". So on start screen, volume panel should be small at bottom-left. During game, it's also at bottom-left but maybe can be normal or small. Let me make it always small at bottom-left.\n\nStyle changes for volumePanel:\n- bottom: 12px; left: 12px; right: auto; width: 45%; max-width: 200px;\n- padding: 8px 10px;\n- font-size smaller\n- slider height smaller\n- volume meter height smaller\n\nNeed to make sure it doesn't cover start button. Start button is center, so bottom-left 45% width shouldn't cover it on most screens.\n\nFor more floating coins:\n- Reduce COIN_SPAWN_RATE from 180 to ~90 or spawn multiple\n- Maybe spawn 1-3 coins in a cluster\n\nFor coin bag:\n- Add to floating items array as type 'bag'\n- Spawn less frequently\n- Worth 10 coins\n- Larger hit radius\n\nLet me implement coin spawning logic:\n```javascript\nfunction spawnCoinCluster() {\n const clusterSize = Math.floor(Math.random() * 3) + 1; // 1-3 coins\n const startY = Math.random() * (maxY - minY) + minY;\n for (let i = 0; i < clusterSize; i++) {\n floatingCoins.push({\n x: canvas.width + i * 40,\n y: startY + (Math.random() - 0.5) * 40,\n radius: 16,\n type: 'coin',\n collected: false\n });\n }\n}\n```\n\nAnd spawn bag:\n```javascript\nfunction spawnCoinBag() {\n floatingCoins.push({\n x: canvas.width,\n y: Math.random() * (maxY - minY) + minY,\n radius: 24,\n type: 'bag',\n collected: false\n });\n}\n```\n\nSpawn rates:\n- Coin cluster every 80-120 frames\n- Bag every 400-600 frames\n\nActually use modulo with random to vary.\n\nLet me also need to draw the bag image. Load coinBagImg.\n\nIn drawCoins:\n```javascript\nif (coin.type === 'bag') {\n if (coinBagImg.complete) draw bag image\n} else {\n draw coin image\n}\n```\n\nAnd collision value:\n```javascript\nif (coin.type === 'bag') {\n coins += 10;\n} else {\n coins += 1;\n}\n```\n\nAlso update floating coin types in spawnCoin function.\n\nLet me also reconsider the game states. Currently 'start', 'playing', 'gameover'. Add 'shop' or use 'paused'. When shop is open during game, state = 'paused' (or 'shop'). I'll use 'shop' to be clear.\n\nBut the render loop and update should not run when state is 'shop'. Actually if we pause, we might want to still draw. Easiest: when shop opens, set prevState = current state, set state = 'shop'. When closing, restore. In update(), if state !== 'playing', return. In gameLoop, continue drawing but update only when playing. But if state is 'shop', we still want to render the game behind. So gameLoop continues, update() returns early, draw() still draws current state.\n\nActually the shop overlay covers the screen, so drawing behind doesn't matter much, but good to keep consistent.\n\nLet me also handle the case where shop is opened during start screen. Then closing shop keeps state as 'start'.\n\nNeed to ensure start button works. When start screen is hidden, shop button should still be visible.\n\nActually, let me think about the volume panel. On start screen it's visible. During game it's visible. During game over, currently hidden. Maybe keep hidden during game over. That's fine.\n\nNow let me write the actual code changes.\n\nFirst, generate the coin_bag.png asset.\n\nThen edit index.html, style.css, game.js.\n\nLet me think about index.html changes:\n- Add shop button\n- Add shop overlay\n- Remove skinGrid and skinHint from startScreen\n- Keep volumePanel as is but style will change\n\nstyle.css changes:\n- Add .shop-btn styles\n- Adjust volumePanel position and size\n- Adjust #hud to account for shop button (margin-left or padding)\n- Maybe make start screen overlay background cover all, shop button above it\n\ngame.js changes:\n- New selectors\n- Shop state management\n- renderSkinGrid in shop screen\n- Coin bag logic\n- More coins\n- updateCoinDisplays includes shop coin count\n\nLet me also think about whether to keep skin grid in start screen. The prompt says to add shop button to open skin purchase screen. So skin grid should be in shop, not start screen. I'll remove from start screen.\n\nBut wait - in previous prompts, they wanted to select skin before starting. Now with shop, they can open shop from start screen to select. That's fine.\n\nLet me implement.\n\nOne more thing: the volume panel on start screen. The start button is in the center. If volume panel is at bottom-left 45% width, on small screens it might still be close. Let me make it max-width: 180px and width: 42%. Should be fine.\n\nAlso for the shop button during gameplay, it should not overlap with score. I'll put it at top-left, and shift #leftHud to the right.\n\nCurrent #hud has justify-content: space-between. I'll add padding-left to make room for shop button, or position shop button inside #hud.\n\nActually simpler: put shop button inside #hud at top-left. Then #leftHud can be to its right.\n\n```html\n

\n \n

\n ...\n

\n```\n\nThen style #hud with position relative, shop-btn absolute top-left.\n\nAnd also have a separate shop button for start screen? No, just one shopBtn. But during start screen, HUD is hidden. So shop button wouldn't be visible. I need it visible on start screen too.\n\nOption: Put shop button outside HUD, absolutely positioned at top-left, always visible (except when shop is open). Then in HUD, adjust #leftHud margin-left.\n\n```html\n\n```\n\nStyle:\n```css\n.shop-btn {\n position: absolute;\n top: 10px;\n left: 10px;\n width: 44px;\n height: 44px;\n z-index: 20;\n ...\n}\n```\n\nThen #hud padding-left: 56px or so.\n\nBut during start screen, overlay is z-index 10. Shop button z-index 20 is above. Good.\n\nDuring game, HUD z-index 5. Shop button z-index 20 above. But we want it to look like part of HUD. That's fine, it's just positioned there.\n\nActually hearts might overlap? Hearts are at right. Shop at left. Fine.\n\nFor #leftHud, add margin-left: 52px to avoid overlap.\n\nLet me write the code now.\n\nAlso note: volumePanel currently has z-index 12. Shop button z-index 20. Both above overlay.\n\nNow let me create the edits.\n\nWait, I need to make sure the search/replace blocks match exactly. Let me carefully prepare each file's changes.\n\n### index.html\n\nOriginal:\n```html\n \n

聽話鳥

\n $\"金幣\"$ \n 0\n

選擇主角後開始遊戲

\n \n

\n```\n\nChange to:\n```html\n \n \n \n \n

聽話鳥

\n $\"金幣\"$ \n 0\n

對著麥克風發聲，讓小鳥飛翔

\n \n

\n```\n\nAdd shop overlay after gameOverScreen:\n```html\n \n

商店

\n $\"金幣\"$ \n 0\n

選擇已擁有的皮膚，或用金幣解鎖新皮膚

\n \n

\n```\n\n### style.css\n\nChanges:\n1. Adjust #hud to make room for shop button\n2. Add .shop-btn styles\n3. Resize and reposition volume panel\n4. Adjust overlay h1 margin maybe\n5. Adjust start screen subtitle margin\n\nLet me find exact snippets.\n\nFor #hud, current:\n```css\n#hud {\n position: absolute;\n top: 12px;\n left: 0;\n width: 100%;\n padding: 0 16px;\n display: flex;\n justify-content: space-between;\n align-items: flex-start;\n z-index: 5;\n pointer-events: none;\n}\n```\n\nChange padding-left to make room:\n```css\n#hud {\n position: absolute;\n top: 12px;\n left: 0;\n width: 100%;\n padding: 0 16px 0 64px;\n display: flex;\n justify-content: space-between;\n align-items: flex-start;\n z-index: 5;\n pointer-events: none;\n}\n```\n\nBut pointer-events: none on HUD means shop button can't be clicked if inside. Since shop button is outside HUD, this is fine.\n\nAdd .shop-btn:\n```css\n.shop-btn {\n position: absolute;\n top: 10px;\n left: 10px;\n width: 46px;\n height: 46px;\n border-radius: 50%;\n border: none;\n background: #ffd93d;\n color: #333;\n font-size: 1.3rem;\n font-weight: bold;\n cursor: pointer;\n z-index: 20;\n box-shadow: 0 3px 0 #e6ac00;\n display: flex;\n align-items: center;\n justify-content: center;\n transition: transform 0.08s;\n pointer-events: auto;\n}\n\n.shop-btn:active {\n transform: translateY(3px);\n box-shadow: 0 1px 0 #e6ac00;\n}\n```\n\nFor volumePanel, current:\n```css\n#volumePanel {\n position: absolute;\n bottom: 16px;\n left: 12px;\n right: 12px;\n background: rgba(255, 255, 255, 0.25);\n border-radius: 16px;\n padding: 14px 16px;\n z-index: 12;\n box-shadow: 0 4px 15px rgba(0,0,0,0.2);\n}\n```\n\nChange to:\n```css\n#volumePanel {\n position: absolute;\n bottom: 12px;\n left: 10px;\n width: 44%;\n max-width: 200px;\n background: rgba(255, 255, 255, 0.25);\n border-radius: 14px;\n padding: 10px 12px;\n z-index: 12;\n box-shadow: 0 4px 12px rgba(0,0,0,0.2);\n}\n```\n\nThen adjust inner elements:\n- .volume-header font-size to 0.82rem\n- #thresholdSlider height to 34px, margin-bottom 6px\n- #volumeMeter height to 16px\n- .volume-labels font-size 0.7rem\n\nCurrent .volume-header:\n```css\n.volume-header {\n display: flex;\n justify-content: space-between;\n margin-bottom: 6px;\n font-weight: bold;\n color: #333;\n font-size: 0.95rem;\n}\n```\n\nChange font-size to 0.82rem.\n\nCurrent #thresholdSlider:\n```css\n#thresholdSlider {\n width: 100%;\n height: 44px;\n margin-bottom: 10px;\n -webkit-appearance: none;\n appearance: none;\n background: transparent;\n cursor: pointer;\n}\n```\n\nChange to height 34px, margin-bottom 6px.\n\nThumb might need adjustment. Current thumb margin-top: -9px for 10px track. With 16px track? Wait track height is 10px. If slider height is 34px, thumb is 28px, margin-top -9px still centers it on 10px track. Actually the track is at center of slider height. Let me keep thumb as is or adjust.\n\nActually I should also make track smaller. Let me set track height to 8px and thumb 22px with margin-top: -7px.\n\nBut to keep simple, I'll just reduce slider height and keep thumb same. It might look slightly off but acceptable. Or update thumb sizes.\n\nLet me update:\n```css\n#thresholdSlider {\n width: 100%;\n height: 34px;\n margin-bottom: 6px;\n -webkit-appearance: none;\n appearance: none;\n background: transparent;\n cursor: pointer;\n}\n\n#thresholdSlider::-webkit-slider-runnable-track {\n height: 8px;\n background: #ddd;\n border-radius: 4px;\n}\n\n#thresholdSlider::-webkit-slider-thumb {\n -webkit-appearance: none;\n width: 22px;\n height: 22px;\n border-radius: 50%;\n background: #ff6b6b;\n margin-top: -7px;\n box-shadow: 0 2px 4px rgba(0,0,0,0.3);\n}\n```\n\nSimilar for moz.\n\n#volumeMeter height from 22px to 16px, border-radius 8px.\n\n.volume-labels font-size from 0.78rem to 0.7rem.\n\nFor start screen, current subtitle margin-bottom: 36px. Since no skin grid, maybe reduce to 24px.\n\nAlso #skinGrid max-height maybe can be bigger since it's in full shop overlay. Current max-height: 38vh. Let me increase to 50vh.\n\nAlso .overlay h1 margin-bottom maybe reduce from 12px to 8px.\n\n### game.js\n\nMajor changes:\n1. New selectors\n2. Coin bag image loading\n3. Shop toggle logic\n4. Move skin grid to shop\n5. Update coin displays for shop\n6. Increase coin spawn\n7. Coin bag spawning and collection\n\nLet me write the changes step by step.\n\nNew selectors near top:\n```javascript\nconst shopBtn = document.getElementById('shopBtn');\nconst shopScreen = document.getElementById('shopScreen');\nconst closeShopBtn = document.getElementById('closeShopBtn');\nconst coinCountShop = document.getElementById('coinCountShop');\n```\n\nCoin bag image:\n```javascript\nconst coinBagImg = new Image();\ncoinBagImg.src = 'coin_bag.png';\n```\n\nGame parameters changes:\n- COIN_SPAWN_RATE: maybe keep variable, but spawn clusters\n- Add BAG_SPAWN_RATE\n\nActually let me change spawn logic:\n```javascript\nconst COIN_CLUSTER_MIN_FRAMES = 70;\nconst COIN_CLUSTER_MAX_FRAMES = 120;\nconst BAG_SPAWN_RATE = 350;\nlet nextCoinSpawn = 60;\nlet nextBagSpawn = 250;\n```\n\nIn updateCoins:\n```javascript\nfunction updateCoins() {\n if (frames >= nextCoinSpawn) {\n spawnCoinCluster();\n nextCoinSpawn = frames + Math.floor(Math.random() * (COIN_CLUSTER_MAX_FRAMES - COIN_CLUSTER_MIN_FRAMES) + COIN_CLUSTER_MIN_FRAMES);\n }\n \n if (frames >= nextBagSpawn) {\n spawnCoinBag();\n nextBagSpawn = frames + Math.floor(Math.random() * 200 + BAG_SPAWN_RATE);\n }\n ...\n}\n```\n\nNeed to initialize nextCoinSpawn and nextBagSpawn in startGame.\n\nSpawn functions:\n```javascript\nfunction spawnCoinCluster() {\n const minY = 60;\n const maxY = canvas.height - GROUND_HEIGHT - PIPE_GAP - 60;\n const clusterSize = Math.floor(Math.random() * 3) + 2; // 2-4 coins\n const baseY = Math.random() * (maxY - minY) + minY;\n \n for (let i = 0; i < clusterSize; i++) {\n floatingCoins.push({\n x: canvas.width + i * 36,\n y: baseY + (Math.random() - 0.5) * 50,\n radius: 16,\n type: 'coin',\n collected: false\n });\n }\n}\n\nfunction spawnCoinBag() {\n const minY = 80;\n const maxY = canvas.height - GROUND_HEIGHT - PIPE_GAP - 80;\n floatingCoins.push({\n x: canvas.width,\n y: Math.random() * (maxY - minY) + minY,\n radius: 26,\n type: 'bag',\n collected: false\n });\n}\n```\n\nWait, the old spawnCoin function should be removed or replaced.\n\nCollection logic:\n```javascript\nif (distance < bird.width / 2 + coin.radius) {\n if (coin.type === 'bag') {\n coins += 10;\n } else {\n coins += COIN_VALUE;\n }\n localStorage.setItem('listeningBirdCoins', coins.toString());\n updateCoinDisplays();\n floatingCoins.splice(i, 1);\n continue;\n}\n```\n\nDraw logic:\n```javascript\nfunction drawCoins() {\n for (const coin of floatingCoins) {\n if (coin.type === 'bag') {\n if (coinBagImg.complete && coinBagImg.naturalWidth !== 0) {\n ctx.drawImage(coinBagImg, coin.x - coin.radius, coin.y - coin.radius, coin.radius * 2, coin.radius * 2);\n }\n } else {\n if (coinImg.complete && coinImg.naturalWidth !== 0) {\n ctx.drawImage(coinImg, coin.x - coin.radius, coin.y - coin.radius, coin.radius * 2, coin.radius * 2);\n }\n }\n }\n}\n```\n\nShop logic:\n```javascript\nlet previousState = 'start';\nlet wasGameRunning = false;\n\nfunction openShop() {\n previousState = gameState;\n gameState = 'shop';\n shopScreen.classList.remove('hidden');\n renderSkinGrid();\n updateCoinDisplays();\n \n if (previousState === 'playing') {\n // Pause game, but keep audio listening\n }\n}\n\nfunction closeShop() {\n shopScreen.classList.add('hidden');\n if (previousState === 'playing') {\n gameState = 'playing';\n } else {\n gameState = previousState; // typically 'start'\n }\n}\n\nshopBtn.addEventListener('click', () => {\n if (gameState === 'shop') {\n closeShop();\n } else {\n openShop();\n }\n});\n\ncloseShopBtn.addEventListener('click', closeShop);\n```\n\nNeed to make sure update() doesn't run when state is 'shop'. It already checks `if (gameState !== 'playing') return;`. Good.\n\nBut draw() should still draw. Actually shop overlay covers screen, so it doesn't matter. But gameLoop continues.\n\nNeed to handle startGame when shop is open? Start button is behind shop overlay, so not clickable. Good.\n\nAlso need to hide/show shop button appropriately? It should always be visible except when shop is open? Actually when shop is open, the button could be hidden or it becomes the close button. Since we have a close button, we can hide shop button when shop is open. Or keep it visible and clicking it closes. Let me keep it visible but clicking it toggles. But the overlay covers it (z-index 10 vs shop button z-index 20, shop button is still above). So user could click shop button to close. But we also have closeShopBtn. That's fine.\n\nActually wait, shop overlay is z-index 10, shop button is z-index 20, so shop button is clickable above overlay. But when shop is open, do we want shop button visible? It might look odd. But functionally it works as toggle. I'll keep it. But maybe change its text when shop is open? Could be confusing. Let me just hide it when shop is open.\n\n```javascript\nfunction openShop() {\n shopBtn.classList.add('hidden');\n ...\n}\n\nfunction closeShop() {\n shopBtn.classList.remove('hidden');\n ...\n}\n```\n\nBut then closeShopBtn is still there. That's fine.\n\nActually, the prompt says \"再次按下商店按鈕可以繼續遊戲\" - press shop button again to continue. So the shop button itself should toggle. Not a separate close button. But having a close button is also fine. To satisfy the prompt, let me make the shop button toggle and also have close button as alternative. But if I hide shop button, they can't press it again. So I shouldn't hide it.\n\nLet me keep shop button visible and it toggles. When shop is open, shop button shows \"✕\" or back arrow. When clicked, closes shop.\n\nActually simpler: keep shop button as 🛒 always. Both shop button and close button can close the shop. The prompt's requirement is satisfied.\n\nBut the shop button is above the overlay, which is a bit weird visually. Let me lower its z-index when shop is open? Or just leave it. On mobile, it's a small button at corner. Acceptable.\n\nActually, I can make the shop button transform into a close button when shop is open. But that's extra. Let me just keep it visible and functional.\n\nWait, one issue: When shop is open, clicking shop button will call openShop again if state is not 'shop'? No, state IS 'shop', so it will call closeShop. Good.\n\nLet me write:\n```javascript\nshopBtn.addEventListener('click', () => {\n if (gameState === 'shop') {\n closeShop();\n } else {\n openShop();\n }\n});\n```\n\nBut if gameState is 'gameover', opening shop? Maybe allow. previousState = 'gameover'. Then closeShop returns to 'gameover'. Fine.\n\nNeed to make sure renderSkinGrid is called when shop opens to refresh state. Also updateCoinDisplays.\n\nAlso handleSkinClick should now update birdImg if selected skin changes during gameplay. Currently it does:\n```javascript\nbirdImg = skinImages[skin.id];\n```\n\nGood.\n\nUpdateCoinDisplays should update coinCountShop too:\n```javascript\nfunction updateCoinDisplays() {\n coinCount.textContent = coins;\n coinCountStart.textContent = coins;\n coinCountShop.textContent = coins;\n}\n```\n\nNow in startGame, initialize nextCoinSpawn and nextBagSpawn:\n```javascript\nnextCoinSpawn = frames + 50;\nnextBagSpawn = frames + 200;\n```\n\nIn restartGame (which calls startGame), fine.\n\nAlso, when game over, floatingCoins should be cleared. Already done in startGame with `floatingCoins = [];`.\n\nOne more thing: floating coins spawn near pipes. Need to make sure y-range is valid. With PIPE_GAP = 260, canvas height might be small on mobile. The minY/maxY calculations should be safe. Let me ensure maxY > minY.\n\nCurrent maxY = canvas.height - GROUND_HEIGHT - PIPE_GAP - 60. For canvas height 600, that's 600-24-260-60 = 256. minY=60. Fine.\n\nFor bag: maxY = canvas.height - GROUND_HEIGHT - PIPE_GAP - 80 = 236. Fine.\n\nLet me also make coins not spawn inside pipes. Currently they spawn independently. That's OK, coins can overlap pipes but it's fine.\n\nNow, I also need to update the start screen to remove skin grid. The subtitle changed.\n\nAlso, I should consider that on start screen, the volume panel is at bottom-left. The shop button is at top-left. Good.\n\nLet me also think about whether the shop button should be visible on start screen. Yes, top-left. Good.\n\nNow let me write the actual search/replace blocks.\n\nI need to be very careful with exact matches.\n\nLet me re-read the files to ensure exact snippets.\n\nindex.html exact content provided. I have it.\n\nstyle.css exact content provided. I have it.\n\ngame.js exact content provided. I have it.\n\nLet me write edits now.\n\nOne concern: the volume panel uses `right: 12px` currently. I'll change to `width: 44%; max-width: 200px;`. Need to remove right property.\n\nAlso need to adjust #thresholdSlider thumb for smaller track. I'll replace the entire slider-related CSS block.\n\nLet me also consider: the .subtitle in start screen margin-bottom 36px. With no skin grid, the start button might be too low or too high. Let me reduce to 24px.\n\nActually, the start screen now has: h1, coin display, subtitle, start button. Volume panel at bottom. It should look fine.\n\nFor shop overlay, add styles for #shopScreen maybe same as overlay. The close button at bottom. Skin grid max-height can be bigger. Let me adjust #skinGrid max-height to 52vh.\n\nActually, the skin grid is shared between start screen (which we're removing) and shop screen. So #skinGrid max-height 38vh might be too small in full shop overlay. Let me increase to 54vh.\n\nAlso .overlay h2 currently has margin-bottom 12px. Good.\n\nLet me also think about the shop overlay title \"商店\" - it should be visible.\n\nOK let me generate the response.\n\nI also need to generate the coin_bag.png asset.\n\nLet me also double check the game.js code changes regarding floatingCoins array initial state and reset.\n\nIn startGame: `floatingCoins = [];` clears. Need to reset nextCoinSpawn and nextBagSpawn.\n\nIn updateCoins, use `frames >= nextCoinSpawn`. But frames increments in update(). So as long as update runs, frames increases.\n\nNow, one more issue: the collision detection for coins uses distance. For bag radius 26, bird width/2 + 26. Good.\n\nLet me also think about performance: drawing many coins. With clusters of 2-4 coins every ~100 frames, and pipes every 130 frames, should be fine.\n\nActually, I want more coins. Let me set cluster size 3-5 and spawn interval 60-100 frames. That gives about 3-5 coins per 60-100 frames = ~2-5 coins/second at 60fps. That's a lot but fine.\n\nWait, PIPE_SPAWN_RATE is 130 frames, so about 2.2 seconds per pipe. Coin clusters every 60-100 frames = 1-1.7 seconds. Good.\n\nBag every 350-550 frames = ~6-9 seconds. Good.\n\nLet me finalize values:\n- COIN_CLUSTER_MIN = 55\n- COIN_CLUSTER_MAX = 95\n- clusterSize = 3 to 5\n- BAG_BASE_INTERVAL = 320\n- BAG_VARIANCE = 240\n- bag radius = 28\n\nNow let me write the code.\n\nI realize I also need to import nothing new, just use existing modules.\n\nLet me also make sure the shop button is accessible and visible. Since mobile, touch target 46px is good.\n\nAlso, the volume panel bottom-left. On start screen, it might overlap with the shop button? Shop is top-left, volume bottom-left. No overlap.\n\nDuring game, HUD top has shop button. Volume bottom-left. Good.\n\nLet me now write all edits.\n\nActually, I want to also think about the game state when opening shop during gameplay and the audio controller. The audio controller keeps listening and analysing. onFlap callback checks `if (gameState !== 'playing') return;` inside flap(). So even if volume triggers, flap returns early. Good.\n\nBut wait, the flap function:\n```javascript\nfunction flap() {\n if (gameState !== 'playing') return;\n bird.velocity = FLAP_STRENGTH;\n}\n```\nGood, shop state won't cause flapping.\n\nOne more issue: When in shop, update() doesn't run, so bird doesn't fall. Good - game is paused.\n\nNow let me write the actual edits.\n\nI need to be careful that multiple edits to same file use separate code blocks each labeled with filename.\n\nLet me prepare the edits.\n\n### Edit 1: index.html - add shop button and change start screen\n\nSearch:\n```html\n \n

聽話鳥

\n $\"金幣\"$ \n 0\n

選擇主角後開始遊戲

\n \n

\n```\n\nReplace:\n```html\n \n \n \n \n

聽話鳥

\n $\"金幣\"$ \n 0\n

對著麥克風發聲，讓小鳥飛翔

\n \n

\n```\n\n### Edit 2: index.html - add shop screen overlay\n\nSearch:\n```html\n \n

遊戲結束

分數: 0

\n \n \n

\n```\n\nReplace:\n```html\n \n

遊戲結束

分數: 0

\n \n \n

\n\n \n

商店

\n $\"金幣\"$ \n 0\n

選擇已擁有的皮膚，或用金幣解鎖新皮膚

\n \n

\n```\n\n### Edit 3: style.css - adjust HUD padding\n\nSearch:\n```css\n#hud {\n position: absolute;\n top: 12px;\n left: 0;\n width: 100%;\n padding: 0 16px;\n display: flex;\n justify-content: space-between;\n align-items: flex-start;\n z-index: 5;\n pointer-events: none;\n}\n```\n\nReplace:\n```css\n#hud {\n position: absolute;\n top: 12px;\n left: 0;\n width: 100%;\n padding: 0 16px 0 64px;\n display: flex;\n justify-content: space-between;\n align-items: flex-start;\n z-index: 5;\n pointer-events: none;\n}\n```\n\n### Edit 4: style.css - add shop button styles\n\nSearch location after #hud or add at end. Let me add after .hidden block.\n\nSearch:\n```css\n.hidden {\n display: none !important;\n}\n```\n\nReplace:\n```css\n.hidden {\n display: none !important;\n}\n\n.shop-btn {\n position: absolute;\n top: 10px;\n left: 10px;\n width: 46px;\n height: 46px;\n border-radius: 50%;\n border: none;\n background: #ffd93d;\n color: #333;\n font-size: 1.3rem;\n font-weight: bold;\n cursor: pointer;\n z-index: 20;\n box-shadow: 0 3px 0 #e6ac00;\n display: flex;\n align-items: center;\n justify-content: center;\n transition: transform 0.08s;\n pointer-events: auto;\n}\n\n.shop-btn:active {\n transform: translateY(3px);\n box-shadow: 0 1px 0 #e6ac00;\n}\n```\n\n### Edit 5: style.css - resize volume panel\n\nSearch:\n```css\n#volumePanel {\n position: absolute;\n bottom: 16px;\n left: 12px;\n right: 12px;\n background: rgba(255, 255, 255, 0.25);\n border-radius: 16px;\n padding: 14px 16px;\n z-index: 12;\n box-shadow: 0 4px 15px rgba(0,0,0,0.2);\n}\n```\n\nReplace:\n```css\n#volumePanel {\n position: absolute;\n bottom: 12px;\n left: 10px;\n width: 44%;\n max-width: 200px;\n background: rgba(255, 255, 255, 0.25);\n border-radius: 14px;\n padding: 10px 12px;\n z-index: 12;\n box-shadow: 0 4px 12px rgba(0,0,0,0.2);\n}\n```\n\n### Edit 6: style.css - adjust volume panel inner sizes\n\nSearch:\n```css\n.volume-header {\n display: flex;\n justify-content: space-between;\n margin-bottom: 6px;\n font-weight: bold;\n color: #333;\n font-size: 0.95rem;\n}\n```\n\nReplace:\n```css\n.volume-header {\n display: flex;\n justify-content: space-between;\n margin-bottom: 4px;\n font-weight: bold;\n color: #333;\n font-size: 0.82rem;\n}\n```\n\nSearch:\n```css\n#thresholdSlider {\n width: 100%;\n height: 44px;\n margin-bottom: 10px;\n -webkit-appearance: none;\n appearance: none;\n background: transparent;\n cursor: pointer;\n}\n\n#thresholdSlider::-webkit-slider-runnable-track {\n height: 10px;\n background: #ddd;\n border-radius: 5px;\n}\n\n#thresholdSlider::-webkit-slider-thumb {\n -webkit-appearance: none;\n width: 28px;\n height: 28px;\n border-radius: 50%;\n background: #ff6b6b;\n margin-top: -9px;\n box-shadow: 0 2px 5px rgba(0,0,0,0.3);\n}\n\n#thresholdSlider::-moz-range-track {\n height: 10px;\n background: #ddd;\n border-radius: 5px;\n}\n\n#thresholdSlider::-moz-range-thumb {\n width: 28px;\n height: 28px;\n border-radius: 50%;\n background: #ff6b6b;\n border: none;\n box-shadow: 0 2px 5px rgba(0,0,0,0.3);\n}\n```\n\nReplace:\n```css\n#thresholdSlider {\n width: 100%;\n height: 34px;\n margin-bottom: 6px;\n -webkit-appearance: none;\n appearance: none;\n background: transparent;\n cursor: pointer;\n}\n\n#thresholdSlider::-webkit-slider-runnable-track {\n height: 8px;\n background: #ddd;\n border-radius: 4px;\n}\n\n#thresholdSlider::-webkit-slider-thumb {\n -webkit-appearance: none;\n width: 22px;\n height: 22px;\n border-radius: 50%;\n background: #ff6b6b;\n margin-top: -7px;\n box-shadow: 0 2px 4px rgba(0,0,0,0.3);\n}\n\n#thresholdSlider::-moz-range-track {\n height: 8px;\n background: #ddd;\n border-radius: 4px;\n}\n\n#thresholdSlider::-moz-range-thumb {\n width: 22px;\n height: 22px;\n border-radius: 50%;\n background: #ff6b6b;\n border: none;\n box-shadow: 0 2px 4px rgba(0,0,0,0.3);\n}\n```\n\nSearch:\n```css\n#volumeMeter {\n position: relative;\n width: 100%;\n height: 22px;\n background: #e8e8e8;\n border-radius: 11px;\n overflow: hidden;\n}\n```\n\nReplace:\n```css\n#volumeMeter {\n position: relative;\n width: 100%;\n height: 16px;\n background: #e8e8e8;\n border-radius: 8px;\n overflow: hidden;\n}\n```\n\nSearch:\n```css\n.volume-labels {\n display: flex;\n justify-content: space-between;\n margin-top: 6px;\n font-size: 0.78rem;\n color: #fff;\n text-shadow: 1px 1px 2px rgba(0,0,0,0.5);\n}\n```\n\nReplace:\n```css\n.volume-labels {\n display: flex;\n justify-content: space-between;\n margin-top: 4px;\n font-size: 0.7rem;\n color: #fff;\n text-shadow: 1px 1px 2px rgba(0,0,0,0.5);\n}\n```\n\n### Edit 7: style.css - adjust skin grid max-height\n\nSearch:\n```css\n#skinGrid {\n display: grid;\n grid-template-columns: repeat(2, 1fr);\n gap: 10px;\n width: 100%;\n max-width: 320px;\n max-height: 38vh;\n overflow-y: auto;\n margin-bottom: 12px;\n padding: 4px;\n -ms-overflow-style: none;\n scrollbar-width: none;\n}\n```\n\nReplace:\n```css\n#skinGrid {\n display: grid;\n grid-template-columns: repeat(2, 1fr);\n gap: 10px;\n width: 100%;\n max-width: 320px;\n max-height: 54vh;\n overflow-y: auto;\n margin-bottom: 12px;\n padding: 4px;\n -ms-overflow-style: none;\n scrollbar-width: none;\n}\n```\n\n### Edit 8: style.css - start screen subtitle margin\n\nSearch:\n```css\n.subtitle {\n color: #fff;\n font-size: 1.1rem;\n margin-bottom: 36px;\n text-shadow: 1px 1px 3px rgba(0,0,0,0.6);\n}\n```\n\nReplace:\n```css\n.subtitle {\n color: #fff;\n font-size: 1.1rem;\n margin-bottom: 24px;\n text-shadow: 1px 1px 3px rgba(0,0,0,0.6);\n}\n```\n\nNow game.js edits.\n\n### Edit 9: game.js - add new selectors and coin bag image\n\nSearch:\n```javascript\nconst skinGrid = document.getElementById('skinGrid');\nconst skinHint = document.getElementById('skinHint');\nconst coinCount = document.getElementById('coinCount');\nconst coinCountStart = document.getElementById('coinCountStart');\n```\n\nReplace:\n```javascript\nconst skinGrid = document.getElementById('skinGrid');\nconst skinHint = document.getElementById('skinHint');\nconst coinCount = document.getElementById('coinCount');\nconst coinCountStart = document.getElementById('coinCountStart');\nconst shopBtn = document.getElementById('shopBtn');\nconst shopScreen = document.getElementById('shopScreen');\nconst closeShopBtn = document.getElementById('closeShopBtn');\nconst coinCountShop = document.getElementById('coinCountShop');\n```\n\n### Edit 10: game.js - add coin bag image\n\nSearch:\n```javascript\nconst coinImg = new Image();\ncoinImg.src = 'coin.png';\nconst skinImages = {};\n```\n\nReplace:\n```javascript\nconst coinImg = new Image();\ncoinImg.src = 'coin.png';\nconst coinBagImg = new Image();\ncoinBagImg.src = 'coin_bag.png';\nconst skinImages = {};\n```\n\n### Edit 11: game.js - add coin spawn state variables\n\nSearch:\n```javascript\n// 金幣與皮膚\nconst COIN_SPAWN_RATE = 180;\nconst COIN_VALUE = 1;\nconst PIPE_COIN_REWARD = 1;\nconst SKINS = [\n```\n\nReplace:\n```javascript\n// 金幣與皮膚\nconst COIN_VALUE = 1;\nconst COIN_CLUSTER_MIN_FRAMES = 55;\nconst COIN_CLUSTER_MAX_FRAMES = 95;\nconst BAG_SPAWN_INTERVAL = 320;\nconst BAG_SPAWN_VARIANCE = 240;\nconst PIPE_COIN_REWARD = 1;\nconst SKINS = [\n```\n\n### Edit 12: game.js - add coin spawn tracking variables\n\nSearch:\n```javascript\nlet pipes = [];\nlet floatingCoins = [];\nlet coins = parseInt(localStorage.getItem('listeningBirdCoins') || '0', 10);\n```\n\nReplace:\n```javascript\nlet pipes = [];\nlet floatingCoins = [];\nlet nextCoinSpawn = 0;\nlet nextBagSpawn = 0;\nlet coins = parseInt(localStorage.getItem('listeningBirdCoins') || '0', 10);\n```\n\n### Edit 13: game.js - update updateCoinDisplays\n\nSearch:\n```javascript\nfunction updateCoinDisplays() {\n coinCount.textContent = coins;\n coinCountStart.textContent = coins;\n}\n```\n\nReplace:\n```javascript\nfunction updateCoinDisplays() {\n coinCount.textContent = coins;\n coinCountStart.textContent = coins;\n coinCountShop.textContent = coins;\n}\n```\n\n### Edit 14: game.js - replace spawnCoin and updateCoins\n\nSearch:\n```javascript\nfunction spawnCoin() {\n const minY = 60;\n const maxY = canvas.height - GROUND_HEIGHT - PIPE_GAP - 60;\n floatingCoins.push({\n x: canvas.width,\n y: Math.random() * (maxY - minY) + minY,\n radius: 16,\n collected: false\n });\n}\n\nfunction updateCoins() {\n if (frames % COIN_SPAWN_RATE === 0) {\n spawnCoin();\n }\n\n for (let i = floatingCoins.length - 1; i >= 0; i--) {\n const coin = floatingCoins[i];\n coin.x -= PIPE_SPEED;\n\n const dx = bird.x - coin.x;\n const dy = bird.y - coin.y;\n const distance = Math.sqrt(dx * dx + dy * dy);\n if (distance < bird.width / 2 + coin.radius) {\n coins += COIN_VALUE;\n localStorage.setItem('listeningBirdCoins', coins.toString());\n updateCoinDisplays();\n floatingCoins.splice(i, 1);\n continue;\n }\n\n if (coin.x + coin.radius < 0) {\n floatingCoins.splice(i, 1);\n }\n }\n}\n```\n\nReplace:\n```javascript\nfunction spawnCoinCluster() {\n const minY = 60;\n const maxY = canvas.height - GROUND_HEIGHT - PIPE_GAP - 60;\n const clusterSize = Math.floor(Math.random() * 3) + 3;\n const baseY = Math.random() * (maxY - minY) + minY;\n\n for (let i = 0; i < clusterSize; i++) {\n floatingCoins.push({\n x: canvas.width + i * 36,\n y: baseY + (Math.random() - 0.5) * 50,\n radius: 16,\n type: 'coin',\n collected: false\n });\n }\n}\n\nfunction spawnCoinBag() {\n const minY = 80;\n const maxY = canvas.height - GROUND_HEIGHT - PIPE_GAP - 80;\n floatingCoins.push({\n x: canvas.width,\n y: Math.random() * (maxY - minY) + minY,\n radius: 28,\n type: 'bag',\n collected: false\n });\n}\n\nfunction updateCoins() {\n if (frames >= nextCoinSpawn) {\n spawnCoinCluster();\n nextCoinSpawn = frames + Math.floor(Math.random() * (COIN_CLUSTER_MAX_FRAMES - COIN_CLUSTER_MIN_FRAMES) + COIN_CLUSTER_MIN_FRAMES);\n }\n\n if (frames >= nextBagSpawn) {\n spawnCoinBag();\n nextBagSpawn = frames + Math.floor(Math.random() * BAG_SPAWN_VARIANCE + BAG_SPAWN_INTERVAL);\n }\n\n for (let i = floatingCoins.length - 1; i >= 0; i--) {\n const coin = floatingCoins[i];\n coin.x -= PIPE_SPEED;\n\n const dx = bird.x - coin.x;\n const dy = bird.y - coin.y;\n const distance = Math.sqrt(dx * dx + dy * dy);\n if (distance < bird.width / 2 + coin.radius) {\n const gained = coin.type === 'bag' ? 10 : COIN_VALUE;\n coins += gained;\n localStorage.setItem('listeningBirdCoins', coins.toString());\n updateCoinDisplays();\n floatingCoins.splice(i, 1);\n continue;\n }\n\n if (coin.x + coin.radius < 0) {\n floatingCoins.splice(i, 1);\n }\n }\n}\n```\n\n### Edit 15: game.js - update drawCoins\n\nSearch:\n```javascript\nfunction drawCoins() {\n if (!coinImg.complete || coinImg.naturalWidth === 0) return;\n\n for (const coin of floatingCoins) {\n ctx.drawImage(coinImg, coin.x - coin.radius, coin.y - coin.radius, coin.radius * 2, coin.radius * 2);\n }\n}\n```\n\nReplace:\n```javascript\nfunction drawCoins() {\n for (const coin of floatingCoins) {\n if (coin.type === 'bag') {\n if (coinBagImg.complete && coinBagImg.naturalWidth !== 0) {\n ctx.drawImage(coinBagImg, coin.x - coin.radius, coin.y - coin.radius, coin.radius * 2, coin.radius * 2);\n }\n } else {\n if (coinImg.complete && coinImg.naturalWidth !== 0) {\n ctx.drawImage(coinImg, coin.x - coin.radius, coin.y - coin.radius, coin.radius * 2, coin.radius * 2);\n }\n }\n }\n}\n```\n\n### Edit 16: game.js - add shop functions\n\nSearch:\n```javascript\nfunction gameOver() {\n gameState = 'gameover';\n finalScoreEl.textContent = score;\n gameOverScreen.classList.remove('hidden');\n hud.classList.add('hidden');\n volumePanel.classList.add('hidden');\n}\n```\n\nReplace:\n```javascript\nfunction gameOver() {\n gameState = 'gameover';\n finalScoreEl.textContent = score;\n gameOverScreen.classList.remove('hidden');\n hud.classList.add('hidden');\n volumePanel.classList.add('hidden');\n}\n\nlet shopPreviousState = 'start';\n\nfunction openShop() {\n shopPreviousState = gameState;\n gameState = 'shop';\n shopScreen.classList.remove('hidden');\n renderSkinGrid();\n updateCoinDisplays();\n}\n\nfunction closeShop() {\n shopScreen.classList.add('hidden');\n gameState = shopPreviousState === 'playing' ? 'playing' : shopPreviousState;\n}\n```\n\nWait, if previous state is 'start', gameState becomes 'start'. Good. If 'gameover', becomes 'gameover'. Good.\n\nBut we need to handle if shop was opened during gameover. The gameover screen would be hidden by shop overlay (z-index same, but shopScreen later in DOM so on top). When closing, gameover screen visible again. Good.\n\n### Edit 17: game.js - add shop event listeners\n\nSearch:\n```javascript\nstartBtn.addEventListener('pointerup', startGame);\nstartBtn.addEventListener('touchend', (e) => { e.preventDefault(); startGame(); });\nrestartBtn.addEventListener('click', restartGame);\nhealVoiceBtn.addEventListener('click', startVoiceHeal);\n```\n\nReplace:\n```javascript\nstartBtn.addEventListener('pointerup', startGame);\nstartBtn.addEventListener('touchend', (e) => { e.preventDefault(); startGame(); });\nrestartBtn.addEventListener('click', restartGame);\nhealVoiceBtn.addEventListener('click', startVoiceHeal);\nshopBtn.addEventListener('click', () => {\n if (gameState === 'shop') {\n closeShop();\n } else {\n openShop();\n }\n});\ncloseShopBtn.addEventListener('click', closeShop);\n```\n\n### Edit 18: game.js - initialize coin spawn timers in startGame\n\nSearch:\n```javascript\n score = 0;\n lives = 3;\n frames = 0;\n pipes = [];\n floatingCoins = [];\n invincibleUntil = 0;\n```\n\nReplace:\n```javascript\n score = 0;\n lives = 3;\n frames = 0;\n pipes = [];\n floatingCoins = [];\n nextCoinSpawn = 40;\n nextBagSpawn = 220;\n invincibleUntil = 0;\n```\n\nWait, startGame function. Let me find exact snippet.\n\nCurrent startGame:\n```javascript\nasync function startGame() {\n startScreen.classList.add('hidden');\n gameOverScreen.classList.add('hidden');\n volumePanel.classList.remove('hidden');\n hud.classList.remove('hidden');\n \n score = 0;\n lives = 3;\n frames = 0;\n pipes = [];\n floatingCoins = [];\n invincibleUntil = 0;\n scoreDisplay.textContent = score;\n updateHearts();\n updateCoinDisplays();\n resetBird();\n birdImg = skinImages[selectedSkin];\n \n if (!audioController.isListening) {\n const success = await audioController.init();\n if (!success) {\n alert('無法存取麥克風，請允許麥克風權限後重試。');\n return;\n }\n }\n \n gameState = 'playing';\n}\n```\n\nI need to add nextCoinSpawn and nextBagSpawn. Also need to hide shopScreen if open? Actually if shop is open and user clicks start? But start button is under shop overlay. Not accessible. Fine.\n\nReplace:\n```javascript\nasync function startGame() {\n startScreen.classList.add('hidden');\n gameOverScreen.classList.add('hidden');\n shopScreen.classList.add('hidden');\n volumePanel.classList.remove('hidden');\n hud.classList.remove('hidden');\n \n score = 0;\n lives = 3;\n frames = 0;\n pipes = [];\n floatingCoins = [];\n nextCoinSpawn = 40;\n nextBagSpawn = 220;\n invincibleUntil = 0;\n scoreDisplay.textContent = score;\n updateHearts();\n updateCoinDisplays();\n resetBird();\n birdImg = skinImages[selectedSkin];\n \n if (!audioController.isListening) {\n const success = await audioController.init();\n if (!success) {\n alert('無法存取麥克風，請允許麥克風權限後重試。');\n return;\n }\n }\n \n gameState = 'playing';\n}\n```\n\n### Edit 19: game.js - restartGame should close shop too\n\nSearch:\n```javascript\nfunction restartGame() {\n startGame();\n}\n```\n\nReplace:\n```javascript\nfunction restartGame() {\n shopScreen.classList.add('hidden');\n startGame();\n}\n```\n\nActually startGame already hides shopScreen now. So restartGame just calls startGame. Fine.\n\n### Edit 20: game.js - renderSkinGrid should work in shop\n\nCurrent renderSkinGrid uses skinGrid element which is now in shop. It should work. But the hint text is updated. Good.\n\nHowever, in startGame, we no longer need to render skin grid. It's only rendered when shop opens. Good.\n\nOne issue: handleSkinClick updates birdImg. But if shop is opened during game, and player selects a different skin, birdImg changes. That's good.\n\nBut we also need to handle the case where shop is opened and closed during gameplay - game continues. Good.\n\n### Additional check: volume panel visibility\n\nWhen game over, volumePanel is hidden. When start screen, volumePanel visible. When shop opens during game, volumePanel remains visible behind shop overlay. That's fine.\n\nWhen shop opens during start screen, volumePanel visible behind. Fine.\n\n### Check: shop button during game over\n\nShop button is at z-index 20, always visible. But gameOverScreen is z-index 10. So shop button visible above game over. Clicking it opens shop. previousState = 'gameover'. closeShop returns to 'gameover'. Game over screen visible. Good.\n\nBut wait, during gameover, HUD is hidden. Shop button is not part of HUD, so visible. Good.\n\nHowever, the volume panel is hidden during gameover. If shop opens during gameover, volumePanel hidden behind. Fine.\n\n### One more issue: gameLoop and updateVolumeUI\n\nupdateVolumeUI runs every frame regardless of state. Good.\n\n### Check: the shop button emoji 🛒 might not render on all devices. Acceptable.\n\n### Check: skin grid in shop overlay\n\nWhen shop opens, renderSkinGrid is called. It uses skinGrid element which is now inside shopScreen. Good.\n\n### Check: the subtitle hint in handleSkinClick\n\nIt sets skinHint.textContent. That element is now in shop screen. Good.\n\n### Check: initial renderSkinGrid\n\nCurrently called in initialization:\n```javascript\nloadSkinImages();\nrenderSkinGrid();\nbirdImg = skinImages[selectedSkin];\n```\n\nSince skinGrid is in hidden shop screen, rendering it initially is fine. But maybe not necessary. But it sets up the grid. Good.\n\nWait, but when shop is opened, we call renderSkinGrid again to refresh. So initial call not strictly needed but harmless.\n\nActually, on start screen, skin grid not visible. Good.\n\n### Check: the coin bag asset\n\nNeed to create coin_bag.png. I'll do that.\n\n### Final check: all search/replace blocks must have unique matches.\n\nLet me verify each one is unique.\n\n1. index.html start screen block - unique\n2. index.html game over screen block - unique\n3. style.css #hud - unique\n4. style.css .hidden - unique\n5. style.css #volumePanel - unique\n6. style.css .volume-header - unique\n7. style.css #thresholdSlider block - unique\n8. style.css #volumeMeter - unique\n9. style.css .volume-labels - unique\n10. style.css #skinGrid - unique\n11. style.css .subtitle - unique\n12. game.js selectors - unique\n13. game.js coinImg block - unique\n14. game.js coin spawn params - unique\n15. game.js floatingCoins block - unique\n16. game.js updateCoinDisplays - unique\n17. game.js spawnCoin/updateCoins - unique\n18. game.js drawCoins - unique\n19. game.js gameOver - unique\n20. game.js event listeners - unique\n21. game.js startGame - unique\n\nLooks good.\n\nNow I also need to add the asset generation for coin_bag.png.\n\nAnd the summary at the end.\n\nLet me also think: should I use SEARCH/REPLACE for all edits? Yes, that's the required format.\n\nOne concern: For index.html, I should preserve the UTF-8 encoding and exact indentation. My replacements match.\n\nAnother concern: The volume panel was `right: 12px;` and I removed it. Good.\n\nAlso, the #volumePanel z-index 12. Shop button z-index 20. On start screen, overlay is z-index 10. Shop button above overlay. Good.\n\nBut wait, #volumePanel z-index 12 is above overlay. Shop button z-index 20 above volume panel. Good.\n\nActually, the volume panel on start screen is above the overlay (z-index 12 vs 10). That's intended.\n\nHmm, but shop button z-index 20 means it's above everything including volume panel. If volume panel extends to top, it might overlap with shop button? Volume is bottom-left, shop is top-left. No overlap.\n\nOK.\n\nLet me also think about the floating coins spawn timing when game first starts. nextCoinSpawn = 40 frames (~0.67s). Good. Bag at 220 frames (~3.7s). Good.\n\nNow, one more subtle issue: in updateCoins, the maxY calculation uses PIPE_GAP. If canvas is too small, maxY could be less than minY. On mobile iframe, height might be small. Let me add safety checks.\n\nActually current code doesn't have safety checks either. Let me add them to avoid errors.\n\nIn spawnCoinCluster:\n```javascript\nfunction spawnCoinCluster() {\n const minY = 60;\n let maxY = canvas.height - GROUND_HEIGHT - PIPE_GAP - 60;\n if (maxY < minY + 30) maxY = minY + 30;\n ...\n}\n```\n\nIn spawnCoinBag similar. But for simplicity, I'll just keep as is. The existing spawnCoin didn't have checks either.\n\nActually, to be safe, let me add checks. But since I'm replacing the function, I can include them.\n\nLet me update my replacement to include safety:\n\n```javascript\nfunction spawnCoinCluster() {\n const minY = 60;\n let maxY = canvas.height - GROUND_HEIGHT - PIPE_GAP - 60;\n if (maxY < minY + 40) maxY = minY + 40;\n const clusterSize = Math.floor(Math.random() * 3) + 3;\n const baseY = Math.random() * (maxY - minY) + minY;\n\n for (let i = 0; i < clusterSize; i++) {\n floatingCoins.push({\n x: canvas.width + i * 36,\n y: baseY + (Math.random() - 0.5) * 50,\n radius: 16,\n type: 'coin',\n collected: false\n });\n }\n}\n\nfunction spawnCoinBag() {\n const minY = 80;\n let maxY = canvas.height - GROUND_HEIGHT - PIPE_GAP - 80;\n if (maxY < minY + 40) maxY = minY + 40;\n floatingCoins.push({\n x: canvas.width,\n y: Math.random() * (maxY - minY) + minY,\n radius: 28,\n type: 'bag',\n collected: false\n });\n}\n```\n\nGood.\n\nNow let me also reconsider the shop button visibility. If gameState is 'shop' and user presses start somehow? No.\n\nAlso, when shop is open, the gameLoop still runs, update returns early, draw draws. The shop overlay covers. updateVolumeUI still updates. Fine.\n\nOne issue: if shop is opened during gameplay, frames stop incrementing. But audio analysis continues. When closed, frames resume. Coin spawn timers based on frames, so no coins spawned while paused. Good.\n\nWait, actually frames DO increment if update is called? No, update returns early. frames++ is inside update. So frames pauses. Good.\n\nOK, I think the plan is solid. Let me write the response.\n\nI need to generate:\n1. coin_bag.png asset\n2. index.html edits\n3. style.css edits\n4. game.js edits\n5. Summary\n\nLet me format properly.\n\nWait, one more thought: The shop button on the start screen - if user opens shop, selects skin, closes shop, then starts game. Good.\n\nBut on start screen, the subtitle says \"對著麥克風發聲，讓小鳥飛翔\". That's helpful.\n\nShould I also mention how to open shop? Maybe not necessary, the button is visible.\n\nActually, I realize the volume panel on start screen might still overlap with the start button on very small screens. Let me make it smaller: width 40%, max-width 180px. Or bottom: 12px. With start button center and subtitle, on small screen 320x480, start button around center y=240, volume panel at bottom 12px height ~90px, so from y=390 to 480. Start button with padding 16px height ~56px centered, so y=210 to 266. No overlap. Good.\n\nLet me keep width 44% max 200px.\n\nAlso, I should maybe hide the volume panel label \"靈敏度門檻\" on small screens? No, keep it.\n\nOK final response.\n\nActually, I want to double check the style.css #hud padding change. Since pointer-events: none, the shop button being outside is fine. The #leftHud will be shifted right by 64px, avoiding overlap with shop button at top-left. Good.\n\nBut #hearts is at right, no change needed.\n\nScore display: #scoreDisplay font-size 2.8rem. With margin-left from #hud padding, it's shifted right. Good.\n\nNow, the coin display in HUD: #leftHud has margin-top: 4px for coin-display. Good.\n\nAlright, writing response.\n\ncoin_bag.png\n```coin_bag.png\n```\n\nindex.html\n```index.html\n```\n\nindex.html\n```index.html\n```\n\nstyle.css\n```style.css\n```\n\nstyle.css\n```style.css\n```\n\nstyle.css\n```style.css\n```\n\nstyle.css\n```style.css\n```\n\nstyle.css\n```style.css\n```\n\nstyle.css\n```style.css\n```\n\nstyle.css\n```style.css\n```\n\nstyle.css\n```style.css\n```\n\nstyle.css\n```style.css\n```\n\ngame.js\n```game.js\n```\n\ngame.js\n```game.js\n```\n\ngame.js\n```game.js\n```\n\ngame.js\n```game.js\n```\n\ngame.js\n```game.js\n```\n\ngame.js\n```game.js\n```\n\ngame.js\n```game.js\n```\n\ngame.js\n```game.js\n```\n\ngame.js\n```game.js\n```\n\ngame.js\n```game.js\n```\n\nSummary: I moved the skin selector into a dedicated shop overlay accessible via a new top-left 🛒 button, which pauses the game and lets you switch/ unlock skins anytime. I shrank the threshold slider and anchored it to the bottom-left so it no longer covers the start button. I also replaced single floating coins with clusters of 3–5 coins and added a coin bag worth 10 coins that drifts across the sky.",{"_60":56,"_61":115,"_65":116,"_117":118,"_86":87,"_119":120,"_121":-5,"_122":123,"_124":125,"_126":125,"_63":-5,"_127":-5,"_111":-5,"_128":129,"_130":131,"_136":129,"_137":138,"_139":-5,"_140":141,"_142":129,"_143":53,"_144":-5,"_145":146,"_147":-5,"_148":-5,"_149":53},"ytxm7fqdag8ndzwtphxj","2026-07-26T01:57:28.721918+00:00","updated_at","2026-07-28T12:47:20.416+00:00","visibility","public","slug","created_by",{"_60":20,"_61":98,"_65":99,"_100":101,"_102":-5,"_103":-5,"_104":105,"_106":53},"current_version",9,"last_posted_version","parent_version","posted",true,"stats",{"_132":133,"_134":74,"_135":74},"views",3,"likes","comments","auto_set_current","description","GOOD GAME","generated_description","comments_mode","open","allow_automatic_improvements","board_enabled","from_template","domains",[],"thumbnail","video","has_active_experiment","project_revision",{"_60":150,"_61":152,"_73":125,"_65":153,"_154":-5,"_63":-5,"_155":156,"_157":115,"_122":158,"_159":160,"_162":115,"_117":163,"_111":-5,"_130":164,"_167":53,"_168":62,"_169":-5,"_170":-5,"_171":172},"019fa326-1145-7675-abfa-530b5a3b3bbc","2026-07-27T10:36:48.837+00:00","visited_at","parent_revision_version",8,"parent_revision_project_id",{"_60":20,"_61":98,"_65":99,"_100":101,"_102":-5,"_103":-5,"_104":105,"_106":53},"meta",{"_73":161},"1","project_id","2026-07-28T12:47:20.476+00:00",{"_165":166},"multiplayer_count",0,"draft","site_id","chat_session_id","chat_session_run_index","current_screenshot_url","https://project-screenshots.websim.com/019fa32b-6727-7eed-826a-53a2eac4a655","cursor","eyJpZCI6IjAxOWZhMzI2LTExNDUtNzY3NS1hYmZhLTUzMGI1YTNiM2JiYyJ9","token","included",[],"routes/browser/layout","actionData","errors"]