.sudoku-wrapper {
    display: flex;
    justify-content: center;
    margin-top: 20px;
    margin-bottom: 20px;
    width: 100%;
}

.sudoku-grid {
    display: grid;
    grid-template-columns: repeat(9, 45px);
    grid-template-rows: repeat(9, 45px);
    gap: 0;
    border: 3px solid #1e293b;
    background-color: #94a3b8;
    box-shadow: 0 4px 10px rgba(0,0,0,0.15);
}

.sudoku-cell {
    background-color: white;
    border: 1px solid #cbd5e1;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5em;
    transition: background-color 0.1s ease;
}

.sudoku-cell.thick-right { border-right: 3px solid #1e293b; }
.sudoku-cell.thick-bottom { border-bottom: 3px solid #1e293b; }

.sudoku-cell.fixed { font-weight: bold; color: #0f172a; }  /* Cifras originales */
.sudoku-cell.guess { color: #2563eb; font-weight: bold; }  /* Cifras del algoritmo */
.sudoku-cell.active { background-color: #fde047; }         /* Cifra actual */