:root{--primary-color:#6366f1;--secondary-color:#ec4899;--accent-color:#f59e0b;--success-color:#10b981;--bg-color:#f8fafc;--text-color:#1e293b;--border-color:#e2e8f0}.solver-hero{padding:60px 0 40px;background:linear-gradient(135deg,#f8fafc 0%,#e2e8f0 100%);text-align:center}.solver-container{padding:40px 0 80px;background-color:white}.solver-layout{display:grid;grid-template-columns:1fr 1fr;gap:40px;align-items:start}@media (max-width:992px){.solver-layout{grid-template-columns:1fr}}.grid-wrapper{display:flex;flex-direction:column;align-items:center;gap:20px}.sudoku-grid{display:grid;grid-template-columns:repeat(9,1fr);width:100%;max-width:450px;aspect-ratio:1 / 1;border:3px solid #1e293b;background-color:#1e293b;gap:1px}.sudoku-cell{background-color:white;display:flex;align-items:center;justify-content:center;font-size:1.5rem;font-weight:600;color:var(--text-color);border:none;outline:none;text-align:center;width:100%;height:100%;padding:0;cursor:pointer;transition:background-color 0.2s}.sudoku-cell:focus{background-color:#e0e7ff}.sudoku-cell.initial{color:#1e293b}.sudoku-cell.solved{color:var(--primary-color)}.sudoku-cell.highlight-target{background-color:#fef3c7}.sudoku-cell.highlight-source{background-color:#dcfce7}.sudoku-cell:nth-child(3n){border-right:2px solid #1e293b}.sudoku-cell:nth-child(9n){border-right:none}.sudoku-grid>div:nth-child(n+19):nth-child(-n+27),.sudoku-grid>div:nth-child(n+46):nth-child(-n+54){border-bottom:2px solid #1e293b}.solver-controls{display:flex;gap:10px;width:100%;max-width:450px}.solver-controls button{flex:1;padding:12px;border-radius:8px;font-weight:600;cursor:pointer;transition:0.3s;display:flex;align-items:center;justify-content:center;gap:8px}.btn-outline{background:transparent;border:2px solid var(--border-color);color:var(--text-color)}.btn-outline:hover{background:var(--border-color)}.hint-card,.instructions-card{background:white;padding:30px;border-radius:12px;box-shadow:0 10px 30px rgba(0,0,0,0.05);margin-bottom:20px;border:1px solid var(--border-color)}.hint-card h3,.instructions-card h3{margin-top:0;margin-bottom:15px;color:var(--primary-color);display:flex;align-items:center;gap:10px}.hint-text{font-size:1.1rem;line-height:1.6;color:var(--text-color);min-height:60px}.technique-info{margin-top:20px;padding-top:20px;border-top:1px solid var(--border-color);font-size:0.9rem;color:#64748b}.instructions-card ul{padding-left:20px;margin-bottom:0}.instructions-card li{margin-bottom:10px;color:#64748b}input::-webkit-outer-spin-button,input::-webkit-inner-spin-button{-webkit-appearance:none;margin:0}input[type=number]{-moz-appearance:textfield}