:root{font-family:"Arial Rounded MT Bold","Microsoft YaHei",sans-serif;color:#164c5b;background:#daf9f5}*{box-sizing:border-box}body{margin:0;min-height:100vh;background:radial-gradient(circle at 15% 10%,#fff7b5 0 5%,transparent 24%),linear-gradient(145deg,#25d7cc,#bdf8eb 55%,#ffe7a8)}button,a{-webkit-tap-highlight-color:transparent}button{font:inherit;color:inherit;cursor:pointer}.shell{width:min(760px,calc(100% - 28px));margin:auto;padding:24px 0 38px}header{display:flex;align-items:center;gap:16px;background:#fffdf4;border:3px solid #fff;border-radius:26px;padding:14px 18px;box-shadow:0 9px 0 #85ccc5}header>div{flex:1;text-align:center}h1{margin:0;font-size:clamp(30px,7vw,52px);color:#ff765f;letter-spacing:.05em}header small{font-weight:800}.brand,#newGame,.scorebar button{border:0;border-radius:14px;padding:11px 14px;background:#eafaf7;text-decoration:none;font-weight:900}#newGame{background:#ffdb58}.scorebar{display:flex;justify-content:center;gap:10px;margin:25px auto 16px}.scorebar div,.scorebar button{min-width:104px;text-align:center;background:#fff;border:3px solid #fff;border-radius:18px;padding:9px 16px;box-shadow:0 5px 0 #8fcfc8}.scorebar span{display:block;font-size:12px}.scorebar strong{font-size:24px}.scorebar button{background:#ff9f88}.scorebar button:disabled{opacity:.45;cursor:not-allowed}.play-card{background:#fffdf3;border:4px solid #fff;border-radius:30px;padding:18px;box-shadow:0 12px 0 #72bbb4;text-align:center}.play-card>p{margin:0 0 14px;font-weight:900}.board{--gap:10px;position:relative;width:min(430px,88vw);aspect-ratio:1;margin:auto;padding:var(--gap);border-radius:24px;background:#75cfc6;touch-action:none;user-select:none;overflow:hidden}.grid-bg{display:grid;grid-template-columns:repeat(4,1fr);gap:var(--gap);height:100%}.grid-bg:before{content:"";grid-column:span 4;background:repeating-conic-gradient(#dff8ef 0 25%,#c9eee7 0 50%) 0/50% 50%;border-radius:15px}.tiles{position:absolute;inset:var(--gap)}.tile{position:absolute;width:calc((100% - 30px)/4);height:calc((100% - 30px)/4);left:calc(var(--c)*(25% + 2.5px));top:calc(var(--r)*(25% + 2.5px));display:grid;place-items:center;border-radius:15px;background:#fff8d1;color:#315865;font-weight:1000;font-size:clamp(25px,8vw,48px);box-shadow:inset 0 -6px rgba(0,0,0,.08);transition:background .15s,color .15s;will-change:transform}.tile[data-v="4"]{background:#ffe89c}.tile[data-v="8"],.tile[data-v="16"]{background:#ffbc75;color:white}.tile[data-v="32"],.tile[data-v="64"]{background:#ff7e70;color:white}.tile[data-v="128"],.tile[data-v="256"]{background:#49d8bd;color:white}.tile[data-v="512"],.tile[data-v="1024"],.tile[data-v="2048"]{background:#7b70e8;color:white;font-size:clamp(18px,6vw,38px)}.mouse-pad{display:grid;grid-template-columns:repeat(3,52px);justify-content:center;gap:6px;margin-top:16px}.mouse-pad button{height:43px;border:0;border-radius:12px;background:#d6f4ef;font-weight:900}.mouse-pad button[data-direction="up"]{grid-column:2}.mouse-pad button[data-direction="left"]{grid-column:1}.mouse-pad button[data-direction="down"]{grid-column:2}.mouse-pad button[data-direction="right"]{grid-column:3}.instructions{margin-top:18px;background:rgba(255,255,255,.9);border-radius:22px;padding:17px 20px;line-height:1.55}.instructions b{font-size:18px}.instructions p{margin:5px 0}@media(max-width:560px){.shell{padding-top:12px}.brand span{display:none}header{padding:10px 12px}.board{--gap:7px}.play-card{padding:12px}.scorebar{margin-top:20px}.scorebar div,.scorebar button{min-width:0;flex:1;padding:8px}.mouse-pad{display:none}}