:root{--primary:#3b82f6;--primary-hover:#2563eb;--accent:#f97316;--accent-hover:#ea580c;--bg:#fff;--text:#1f2937;--text-secondary:#6b7280;--border:#e5e7eb;--cell-bg:#f9fafb;--cell-hover:#f3f4f6;--winner-bg:#dbeafe}*,:before,:after{box-sizing:border-box}body{-webkit-font-smoothing:antialiased;background:var(--bg);color:var(--text);margin:0;font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif}.screen{flex-direction:column;justify-content:center;align-items:center;min-height:100vh;padding:1rem;display:flex}.game-container{width:100%;max-width:500px}.game-header{text-align:center;margin-bottom:2rem}.game-title{color:var(--primary);margin:0 0 .5rem;font-size:2.5rem;font-weight:700}.game-status{color:var(--text);min-height:2rem;margin:.5rem 0;font-size:1.25rem;font-weight:600}.game-status.won{color:var(--accent)}.turn-indicator{color:var(--text-secondary);font-size:1rem}.game-board{aspect-ratio:1;grid-template-columns:repeat(3,1fr);gap:.75rem;max-width:400px;margin:2rem auto;display:grid}.cell{background:var(--cell-bg);border:2px solid var(--border);cursor:pointer;aspect-ratio:1;-webkit-user-select:none;user-select:none;border-radius:.5rem;justify-content:center;align-items:center;font-size:3rem;font-weight:700;transition:all .2s;display:flex}.cell:hover:not(.filled):not(.disabled){background:var(--cell-hover);border-color:var(--primary);transform:scale(1.05)}.cell.filled{cursor:default}.cell.disabled{cursor:not-allowed;opacity:.6}.cell.winner{background:var(--winner-bg);border-color:var(--accent);animation:.5s ease-in-out pulse}.cell-x{color:var(--primary)}.cell-o{color:var(--accent)}@keyframes pulse{0%,to{transform:scale(1)}50%{transform:scale(1.1)}}.game-actions{text-align:center;margin-top:2rem}.btn{background:var(--primary);color:#fff;cursor:pointer;border:none;border-radius:.5rem;padding:.75rem 2rem;font-size:1rem;font-weight:600;transition:background .2s}.btn:hover{background:var(--primary-hover)}.btn:active{transform:translateY(1px)}.btn-accent{background:var(--accent)}.btn-accent:hover{background:var(--accent-hover)}@media (width<=640px){.game-title{font-size:2rem}.game-status{font-size:1.125rem}.cell{font-size:2rem}.game-board{gap:.5rem}}