/* =========================================
   SUDOKU BUILDER CSS
   ========================================= */

.sudoku-builder-container {
    display: flex;
    flex-wrap: wrap;
    gap: 2rem;
    margin-top: 2rem;
}

.sudoku-left-panel {
    flex: 1;
    min-width: 320px;
    background: var(--color-surface-container-lowest);
    border: 1px solid var(--color-outline-variant);
    padding: 2rem;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.sudoku-right-panel {
    width: 300px;
    background: var(--color-surface-container-lowest);
    border: 1px solid var(--color-outline-variant);
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.sudoku-grid {
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    grid-template-rows: repeat(9, 1fr);
    gap: 0;
    border: 3px solid var(--color-on-background);
    background: var(--color-outline-variant);
    width: 100%;
    max-width: 450px;
    aspect-ratio: 1;
}

.sudoku-cell {
    background: var(--color-surface-container-lowest);
    border-right: 1px solid var(--color-outline-variant);
    border-bottom: 1px solid var(--color-outline-variant);
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-headline);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-on-background);
    cursor: pointer;
    user-select: none;
    transition: background 0.1s;
}

.sudoku-cell:nth-child(3n) { border-right: 3px solid var(--color-on-background); }
.sudoku-cell:nth-child(9n) { border-right: none; }
.sudoku-cell:nth-child(n+19):nth-child(-n+27),
.sudoku-cell:nth-child(n+46):nth-child(-n+54) {
    border-bottom: 3px solid var(--color-on-background);
}
.sudoku-cell:nth-child(n+73) { border-bottom: none; }

.sudoku-cell.selected {
    background: var(--color-tertiary-container);
    color: var(--color-on-tertiary-container);
}

.sudoku-cell.error {
    background: var(--color-error-container);
    color: var(--color-on-error-container);
}

.sudoku-numpad {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 0.5rem;
}

.sudoku-numpad-btn {
    background: var(--color-surface-container-high);
    border: 1px solid var(--color-outline-variant);
    padding: 1rem;
    font-family: var(--font-headline);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-on-surface);
    cursor: pointer;
    border-radius: 4px;
    transition: all 0.2s;
}

.sudoku-numpad-btn:hover {
    background: var(--color-primary);
    color: var(--color-on-primary);
}

.sudoku-numpad-btn.clear-btn {
    grid-column: span 3;
    background: var(--color-error-container);
    color: var(--color-on-error-container);
}

.sudoku-numpad-btn.clear-btn:hover {
    background: var(--color-error);
    color: var(--color-on-error);
}