.sudoku-container{max-width:900px;margin:0 auto;padding:20px}.sudoku-controls{text-align:center;margin-bottom:20px}.difficulty-btn-sudoku.active{background:#4CAF50;color:white}#notes-toggle.active{background:#4CAF50;color:white}.sudoku-board{display:grid;grid-template-columns:repeat(9,50px);gap:0;margin:0 auto 20px;border:3px solid #000;background:transparent;width:456px;height:456px}.sudoku-cell{width:50px;height:50px;border:1px solid #999;display:flex;align-items:center;justify-content:center;font-size:24px;font-weight:bold;background:#fff;color:#000;cursor:pointer;position:relative;user-select:none}.sudoku-cell:focus{outline:2px solid #4CAF50;background:#e8f5e9;z-index:10}.sudoku-cell.selected{background:#e8f5e9;outline:2px solid #4CAF50;z-index:10}.sudoku-cell.given{background:#f5f5f5;font-weight:bold;cursor:default;color:#000}.sudoku-cell.error{background:#ffebee;color:#f44336}.sudoku-cell.highlight{background:#fff9c4}.sudoku-cell:nth-child(3n){border-right:2px solid #000}.sudoku-cell:nth-child(n+19):nth-child(-n+27),.sudoku-cell:nth-child(n+46):nth-child(-n+54){border-bottom:2px solid #000}.sudoku-notes{position:absolute;top:2px;left:2px;right:2px;bottom:2px;display:grid;grid-template-columns:repeat(3,1fr);grid-template-rows:repeat(3,1fr);gap:1px;font-size:8px;padding:1px;pointer-events:none}.sudoku-note{display:flex;align-items:center;justify-content:center;color:#666}.sudoku-number-pad{display:flex;justify-content:center;gap:10px;margin-bottom:20px;flex-wrap:wrap}.number-btn{width:50px;height:50px;font-size:20px;font-weight:bold;border:2px solid #4CAF50;background:#fff;color:#4CAF50;cursor:pointer;border-radius:5px;transition:all 0.2s}.number-btn:hover{background:#4CAF50;color:#fff}.number-btn:active{transform:scale(0.95)}.game-message{text-align:center;margin-top:25px;font-size:24px;font-weight:700;padding:15px;border-radius:12px;background:rgba(255,255,255,0.95);box-shadow:0 4px 15px rgba(0,0,0,0.1);display:none}.game-message.show{display:block}.game-message.win{color:#4CAF50;background:linear-gradient(135deg,#a8edea 0%,#fed6e3 100%)}