.sudoku-container{max-width:400px;margin:0 auto;padding:20px;background:#f5f5f5;border-radius:12px;min-height:60vh;display:flex;flex-direction:column}.game-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:20px;background:#fff;padding:15px;border-radius:8px;box-shadow:0 2px 8px #0000001a}.game-header h1{margin:0;font-size:1.5rem;color:#2c3e50}.game-info{display:flex;align-items:center;gap:15px}.timer{font-family:monospace;font-size:1.2rem;font-weight:700}.difficulty-selector{display:flex;gap:4px}.difficulty-btn{padding:6px 12px;background-color:#e0e0e0;border:none;border-radius:4px;cursor:pointer;font-size:.85rem;font-weight:400}.difficulty-btn.active{background-color:#4a90e2;color:#fff}.game-board{margin:20px 0;display:grid;grid-template-rows:repeat(9,1fr);gap:0;border:2px solid #000;border-radius:4px;overflow:hidden}.board-row{display:grid;grid-template-columns:repeat(9,1fr)}.cell{width:100%;height:44px;display:flex;align-items:center;justify-content:center;font-size:1.5rem;font-weight:400;color:#000;border:1px solid #ccc;background-color:#fff;transition:background-color .15s ease;cursor:pointer;-webkit-user-select:none;user-select:none}.cell:hover{background-color:#f0f0f0}.cell.selected{background-color:#e6f2ff;outline:2px solid #2196f3;outline-offset:-2px;z-index:1}.cell[data-col="2"],.cell[data-col="5"]{border-right:2px solid #000}.board-row[data-row="2"] .cell,.board-row[data-row="5"] .cell{border-bottom:2px solid #000}.controls{display:flex;justify-content:center;gap:10px;margin:15px 0;padding:10px;background:#f9f9f9;border-radius:6px}.control-btn{padding:10px 20px;background-color:#4a90e2;color:#fff;border:none;border-radius:4px;cursor:pointer;font-size:1rem}.control-btn:hover{background-color:#357ab8}.control-btn:disabled{background-color:#b0c4de;cursor:not-allowed}.number-pad{display:grid;grid-template-columns:repeat(5,1fr);gap:10px;margin-top:20px;padding:15px;background:#fff;border-radius:8px;box-shadow:0 2px 8px #0000001a}.number-pad button{padding:12px;font-size:1.5rem;background-color:#e0e0e0;border:none;border-radius:6px;cursor:pointer;font-weight:400}.number-pad button:hover{background-color:#d0d0d0}.number-pad button:active{background-color:silver}.win-overlay{position:fixed;top:0;left:0;width:100%;height:100%;background:#000000b3;display:flex;justify-content:center;align-items:center;z-index:1000}.win-message{background:#fff;padding:30px;border-radius:10px;text-align:center;max-width:80%}.win-message h2{margin-top:0;color:#2c3e50}.win-message p{margin:15px 0;font-size:1.1rem}.win-message button{background-color:#4a90e2;color:#fff;padding:10px 20px;border:none;border-radius:4px;cursor:pointer;font-size:1rem}.win-message button:hover{background-color:#357ab8}