:root{--bg:#0b0e14;--panel:#121826;--text:#e6e6e6;--muted:#9aa4b2;--accent:#6ee7b7;--grid:#1f2937}
*{box-sizing:border-box}
html,body{height:100%}
body{margin:0;font-family:Inter,system-ui,-apple-system,Segoe UI,Roboto,Helvetica,Arial,sans-serif;background:linear-gradient(160deg,#0b0e14,#101624);color:var(--text);display:flex;align-items:center;justify-content:center}
.app{width:min(100%,960px);padding:16px}
.header{display:flex;align-items:center;justify-content:center;margin-bottom:12px}
.header h1{font-size:22px;letter-spacing:.5px;margin:0;font-weight:800}
.main{display:flex;justify-content:center}
.game{display:grid;grid-template-columns:auto 220px;gap:16px;align-items:start}
canvas#board{background:var(--panel);border-radius:10px;box-shadow:0 10px 30px rgba(0,0,0,.35);outline:1px solid #101624}
.sidebar{display:flex;flex-direction:column;gap:12px}
.panel{background:rgba(18,24,38,.9);backdrop-filter:blur(6px);border:1px solid #1a2233;border-radius:12px;padding:12px}
.panel .row{display:flex;justify-content:space-between;padding:6px 0;border-bottom:1px dashed rgba(255,255,255,.06)}
.panel .row:last-child{border-bottom:0}
.label{color:var(--muted);font-size:12px}
#score,#lines,#level{font-weight:700}
canvas#next{width:120px;height:120px;background:#0f1626;border-radius:8px;border:1px solid #1a2233;display:block;margin-top:8px}
.controls{display:grid;grid-template-columns:repeat(3,1fr);gap:8px}
.btn{appearance:none;border:1px solid #2a3347;background:#0f1626;color:var(--text);padding:8px 10px;border-radius:8px;cursor:pointer;font-weight:600}
.btn[disabled]{opacity:.5;cursor:not-allowed}
.btn:hover:not([disabled]){border-color:#3a4661}
.help{display:grid;grid-template-columns:1fr 1fr;gap:4px 10px;font-size:12px;color:var(--muted)}
.help .k{font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;color:#cbd5e1;background:#0f1626;border:1px solid #1a2233;border-radius:6px;padding:2px 6px;display:inline-block}
.footer{text-align:center;margin-top:12px;color:#93a1b1;font-size:12px}

@media (max-width: 720px){
    .game{grid-template-columns:1fr}
    .sidebar{order:-1}
}

.overlay{position:fixed;inset:0;background:rgba(0,0,0,.55);display:flex;align-items:center;justify-content:center;z-index:50}
.overlay.hidden{display:none}
.overlay-card{background:rgba(18,24,38,.96);border:1px solid #1a2233;border-radius:14px;padding:20px;min-width:280px;max-width:92vw;text-align:center;box-shadow:0 10px 30px rgba(0,0,0,.45)}
.overlay-card h2{margin:0 0 8px 0;font-size:20px}
.overlay-card p{margin:0 0 14px 0;color:#b6c2d2}
.overlay-actions{display:flex;gap:8px;justify-content:center}