html,body,#root,.app-container{height:100%;width:100%;margin:0;padding:0;box-sizing:border-box;font-family:Segoe UI,Arial,sans-serif;background:linear-gradient(135deg,#f5f7fa,#c3cfe2)}.app-container{display:flex;flex-direction:column;align-items:center;justify-content:center;height:100vh;position:relative}.board-3d{width:500px;height:500px;margin:0 auto;border-radius:16px;box-shadow:0 8px 32px #3c3c7826;background:#fff3;overflow:hidden}.ui-overlay{position:absolute;top:30px;left:0;width:100%;display:flex;flex-direction:column;align-items:center;z-index:10;pointer-events:none}.winner-message{background:#fffffff2;color:#333;font-size:2rem;padding:1rem 2rem;border-radius:12px;margin-bottom:1rem;box-shadow:0 2px 8px #00000014;pointer-events:auto}.restart-btn{background:#64b5f6;color:#fff;border:none;font-size:1.2rem;padding:.7rem 2rem;border-radius:8px;cursor:pointer;transition:background .2s;pointer-events:auto}.restart-btn:hover{background:#1976d2}.player-names-row{display:flex;justify-content:space-between;align-items:center;width:100%;margin:1rem auto 2rem}.player-name{flex:1;display:flex;flex-direction:column;align-items:center}.player-x label{color:#e57373;font-weight:700}.player-o label{color:#64b5f6;font-weight:700}.player-name input{margin-top:.5rem;padding:.4rem 1rem;border-radius:6px;border:1px solid #ccc;font-size:1rem;text-align:center}.difficulty-selector{text-align:center;margin-bottom:1rem;padding:1rem;background:#ffffff1a;border-radius:12px;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}.difficulty-selector h3{margin:0 0 1rem;color:#333;font-size:1.2rem}.difficulty-buttons{display:flex;justify-content:center;gap:1rem;margin-bottom:1rem}.difficulty-btn{padding:.5rem 1.5rem;border:2px solid #64b5f6;background:#fff;color:#64b5f6;border-radius:8px;cursor:pointer;font-weight:700;transition:all .2s}.difficulty-btn:hover:not(:disabled){background:#64b5f6;color:#fff}.difficulty-btn.active{background:#64b5f6;color:#fff}.difficulty-btn:disabled{opacity:.5;cursor:not-allowed}.difficulty-info{font-size:.9rem;color:#666}.difficulty-info p{margin:.2rem 0}.timer{text-align:center;margin:1rem 0;padding:.5rem 1rem;background:#ffffffe6;border-radius:8px;box-shadow:0 2px 8px #0000001a}.timer-label{font-size:.9rem;color:#666;margin-bottom:.3rem}.timer-value{font-size:2rem;font-weight:700;color:#333}.timer-value.warning{color:#e57373;animation:pulse 1s infinite}@keyframes pulse{0%,to{opacity:1}50%{opacity:.7}}.undo-section{display:flex;justify-content:center;align-items:center;margin:1rem 0}.undo-btn{padding:.7rem 1.5rem;background:#ff9800;color:#fff;border:none;border-radius:8px;cursor:pointer;font-weight:700;font-size:1rem;transition:all .2s;box-shadow:0 2px 8px #ff98004d}.undo-btn:hover{background:#f57c00;transform:translateY(-2px);box-shadow:0 4px 12px #ff980066}.undo-btn:active{transform:translateY(0)}