*{box-sizing:border-box;}html,body{height:100%;margin:0;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Arial,sans-serif;background:linear-gradient(135deg,#f8fafc,#dbeafe);}body{display:flex;align-items:flex-start;justify-content:center;padding:24px;color:#111;}h1{margin:0 0 12px;font-size:clamp(1.8rem,2.5vw,2.6rem);text-align:center;font-weight:600;letter-spacing:1px;}h1 small{display:block;font-size:.55em;font-weight:400;letter-spacing:0;color:#64748b;margin-top:4px;}main.app{max-width:520px;width:100%;background:#fff;border-radius:20px;padding:28px 30px 36px;box-shadow:0 12px 40px -10px rgba(30,41,59,.15),0 4px 18px -4px rgba(30,41,59,.08);}section.controls{display:flex;flex-wrap:wrap;gap:12px;justify-content:space-between;align-items:center;margin-bottom:12px;}button{cursor:pointer;font:600 15px/1.2 inherit;border:0;padding:10px 18px;border-radius:12px;background:#e2e8f0;color:#334155;transition:.18s ease;position:relative;box-shadow:0 2px 4px rgba(0,0,0,.08);}button:hover,button:focus-visible{background:#cbd5e1;outline:2px solid #94a3b8;outline-offset:1px;}button:active{transform:translateY(1px);}button.mode-btn.active{background:#2563eb;color:#fff;box-shadow:0 4px 10px -2px rgba(37,99,235,.4);}button.restart{background:#f59e0b;color:#fff;}button.restart:hover{background:#d97706;}section.status{font-size:18px;margin:12px 0 18px;text-align:center;font-weight:500;}span.turn{display:inline-block;min-width:1.4em;text-align:center;color:#2563eb;font-weight:700;}section.board{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;width:min(100%,420px);margin:0 auto;}button.cell{width:100%;aspect-ratio:1/1;font:700 clamp(2.2rem,7.5vw,3.8rem)/1 "SF Mono",monospace;border-radius:18px;background:#f1f5f9;color:#0f172a;display:flex;align-items:center;justify-content:center;position:relative;transition:background .25s,transform .25s;}button.cell.empty:hover{background:#e2e8f0;}button.cell.winning{background:#16a34a!important;color:#fff;animation:pulse .9s ease-in-out infinite alternate;}@keyframes pulse{from{box-shadow:0 0 0 0 rgba(16,185,129,.25);}to{box-shadow:0 0 0 12px rgba(16,185,129,0);} }dialog.result-dialog{border:0;border-radius:20px;padding:28px 32px;max-width:320px;box-shadow:0 18px 48px -12px rgba(15,23,42,.35),0 6px 24px -8px rgba(30,41,59,.25);background:#fff;}dialog.result-dialog::backdrop{background:rgba(15,23,42,.45);backdrop-filter:blur(3px);}dialog.result-dialog p{margin:0 0 18px;font-size:22px;font-weight:600;text-align:center;}footer.footer{margin-top:34px;font-size:13px;text-align:center;color:#64748b;}footer a{color:#2563eb;text-decoration:none;}footer a:hover{text-decoration:underline;}@media (max-width:560px){main.app{padding:24px 22px 30px;border-radius:16px;}section.board{gap:8px;}button.cell{border-radius:14px;}}