:root{--page:#f7f1e7;--surface:#fffaf1;--board:#b9a58f;--empty:#fffaf161;--ink:#3c3029;--muted:#8a776a;--accent:#e47a42;--accent-dark:#b9512a;--line:#3c302921;color:var(--ink);background:var(--page);font-family:-apple-system,BlinkMacSystemFont,Segoe UI,PingFang SC,Microsoft YaHei,sans-serif}*{box-sizing:border-box}html,body{background:var(--page);min-width:0;min-height:100%;margin:0}body{min-height:100dvh}button{font:inherit}.page{min-height:100dvh;padding:max(24px, env(safe-area-inset-top)) max(16px, env(safe-area-inset-right)) max(24px, env(safe-area-inset-bottom)) max(16px, env(safe-area-inset-left));place-items:center;display:grid}.game-shell{width:min(100%,560px)}.game-header{justify-content:space-between;align-items:end;gap:20px;margin-bottom:22px;display:flex}.eyebrow{color:var(--accent-dark);letter-spacing:.12em;text-transform:uppercase;margin:0 0 6px;font-size:12px;font-weight:800}h1,h2{letter-spacing:-.04em;margin:0}h1{font-size:clamp(38px,10vw,62px);line-height:.95}h2{font-size:32px}.subtitle{color:var(--muted);margin:14px 0 0;font-size:15px;line-height:1.5}.score-row{flex-shrink:0;gap:8px;display:flex}.score-box{border:1px solid var(--line);background:var(--surface);text-align:center;border-radius:12px;min-width:74px;padding:9px 10px 8px}.score-box span{color:var(--muted);font-size:11px;font-weight:700;display:block}.score-box strong{margin-top:3px;font-size:22px;line-height:1;display:block}.toolbar{justify-content:space-between;align-items:center;gap:12px;margin-bottom:12px;display:flex}.status{color:var(--muted);margin:0;font-size:13px}.toolbar-actions,.overlay-actions{gap:8px;display:flex}.button{border:1px solid var(--line);cursor:pointer;border-radius:10px;min-height:42px;padding:0 14px;font-size:13px;font-weight:800;transition:transform .12s,background .12s,opacity .12s}.button:active:not(:disabled){transform:translateY(1px)}.button:focus-visible{outline-offset:2px;outline:3px solid #e47a4266}.button:disabled{cursor:not-allowed;opacity:.42}.button-primary{border-color:var(--accent);color:#fffaf1;background:var(--accent)}.button-primary:hover:not(:disabled){background:var(--accent-dark)}.button-quiet{color:var(--ink);background:var(--surface)}.button-quiet:hover:not(:disabled){background:#f0e4d2}.board-wrap{position:relative}.board{background:var(--board);touch-action:none;-webkit-user-select:none;user-select:none;border-radius:16px;grid-template-columns:repeat(4,1fr);gap:10px;padding:10px;display:grid}.tile{aspect-ratio:1;background:var(--empty);color:var(--ink);border-radius:10px;place-items:center;font-size:clamp(25px,8vw,48px);font-weight:900;line-height:1;display:grid}.tile span{transform:translateY(-1px)}.tile-2{background:#eee0c9}.tile-4{background:#ebd6ad}.tile-8{color:#fffaf1;background:#eda56a}.tile-16{color:#fffaf1;background:#e8864f}.tile-32{color:#fffaf1;background:#df623e}.tile-64{color:#fffaf1;background:#cc442e}.tile-128,.tile-256{color:#fffaf1;background:#b7a03a;font-size:clamp(22px,7vw,40px)}.tile-512,.tile-1024,.tile-2048{color:#fffaf1;background:#8d6b31;font-size:clamp(20px,6vw,36px)}.tile-4096,.tile-8192{color:#fffaf1;background:#594332;font-size:clamp(18px,5.5vw,32px)}.overlay{z-index:10;-webkit-backdrop-filter:blur(2px);backdrop-filter:blur(2px);background:#3c30293d;place-items:center;padding:20px;display:grid;position:fixed;inset:0}.overlay[hidden]{display:none}.overlay-card{background:var(--surface);text-align:center;border:1px solid #3c302933;border-radius:16px;width:min(340px,100vw - 40px);max-height:calc(100dvh - 40px);padding:26px 20px 20px;overflow:auto;box-shadow:0 20px 48px #3c30293d}.overlay-card p:not(.eyebrow){color:var(--muted);margin:10px 0 20px;line-height:1.5}.overlay-actions{justify-content:center}.game-footer{color:var(--muted);justify-content:space-between;gap:12px;margin-top:13px;font-size:12px;display:flex}.game-footer strong{color:var(--ink)}@media (width<=480px){.page{padding-left:12px;padding-right:12px}.game-header{flex-direction:column;align-items:start;gap:15px}.score-row{width:100%}.score-box{flex:1}.toolbar{flex-direction:column;align-items:start}.toolbar-actions{width:100%}.toolbar-actions .button{flex:1}.game-footer{flex-direction:column}}@media (height<=700px){.page{--compact-shell:min(560px, calc(100vw - 24px), calc(100dvh - 202px));padding-top:max(12px, env(safe-area-inset-top));padding-bottom:max(12px, env(safe-area-inset-bottom))}.game-shell{width:var(--compact-shell)}.game-header{align-items:flex-start;gap:10px;margin-bottom:12px}.game-header>div:first-child{min-width:0}.eyebrow{margin-bottom:4px;font-size:10px}h1{font-size:clamp(32px,9vw,44px)}.subtitle{margin-top:6px;font-size:12px;line-height:1.35}.score-row{gap:6px}.score-box{border-radius:10px;min-width:62px;padding:7px 6px 6px}.score-box span{font-size:10px}.score-box strong{font-size:18px}.toolbar{gap:8px;margin-bottom:8px}.status{font-size:12px}.button{min-height:38px;padding:0 11px;font-size:12px}.board{border-radius:13px;gap:7px;padding:7px}.tile{border-radius:8px;font-size:clamp(21px,7vw,38px)}.tile-128,.tile-256{font-size:clamp(19px,6vw,32px)}.tile-512,.tile-1024,.tile-2048{font-size:clamp(17px,5.5vw,29px)}.tile-4096,.tile-8192{font-size:clamp(15px,5vw,26px)}.game-footer{margin-top:8px;font-size:11px}}@media (prefers-reduced-motion:reduce){.button{transition:none}}