/* ============================================
   Futoshiki CSS
   Board uses a (2N-1)×(2N-1) CSS grid where:
   - Odd-indexed tracks = game cells
   - Even-indexed tracks = constraint slots
   ============================================ */

.futoshiki-board {
    display: grid;
    gap: 0;
    /* grid-template-columns and grid-template-rows are set dynamically by JS */
    position: relative;
    border-radius: 12px;
    background: var(--color-bg-card);
    padding: 8px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
}

/* ─── Game cells ─── */
.futoshiki-cell {
    width: 100%;
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    border-radius: 6px;
    border: 1.5px solid var(--color-border-main, #CBD5E1);
    background: var(--color-bg-primary, #fff);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-text-main, #1E293B);
    outline: none;
    user-select: none;
    cursor: pointer;
    transition: background 0.12s, border-color 0.12s, box-shadow 0.12s;
}

.futoshiki-cell:focus {
    box-shadow: 0 0 0 2px var(--color-primary, #4F46E5);
    border-color: var(--color-primary, #4F46E5);
    z-index: 2;
}

.futoshiki-cell--selected {
    background: var(--color-selected-bg, #EEF2FF);
    border-color: var(--color-primary, #4F46E5);
}

.futoshiki-cell--given {
    background: var(--color-bg-secondary, #F1F5F9);
    color: var(--color-text-main, #1E293B);
    cursor: default;
    border-color: var(--color-border-main, #CBD5E1);
}

.futoshiki-cell--given:focus {
    box-shadow: none;
    border-color: var(--color-border-main, #CBD5E1);
}

.futoshiki-cell--empty {
    color: transparent;
}

.futoshiki-cell--related {
    background: var(--color-selected-bg-light, #F5F3FF);
}

.futoshiki-cell--error {
    background: var(--color-error-bg, #FEF2F2) !important;
    border-color: var(--color-error, #EF4444) !important;
    color: var(--color-error-text, #DC2626);
}

.futoshiki-cell--hint-target {
    border-color: var(--color-warning, #F59E0B) !important;
    background: var(--color-warning-bg, #FFFBEB) !important;
    animation: futoshiki-hint-pulse 1.4s ease-in-out infinite;
}

.futoshiki-cell--hint-flash {
    animation: futoshiki-hint-flash 1.8s ease-out forwards;
}

@keyframes futoshiki-hint-pulse {
    0%, 100% { box-shadow: 0 0 0 2px color-mix(in srgb, var(--color-warning, #F59E0B) 60%, transparent); }
    50% { box-shadow: 0 0 0 4px color-mix(in srgb, var(--color-warning, #F59E0B) 30%, transparent); }
}

@keyframes futoshiki-hint-flash {
    0%   { background: var(--color-success-bg, #F0FDF4); border-color: var(--color-success, #22C55E); }
    60%  { background: var(--color-success-bg, #F0FDF4); border-color: var(--color-success, #22C55E); }
    100% { background: var(--color-bg-primary, #fff); border-color: var(--color-border-main, #CBD5E1); }
}

/* ─── Cell value and notes ─── */
.futoshiki-cell__value {
    pointer-events: none;
    line-height: 1;
}

.futoshiki-cell--with-notes .futoshiki-cell__value {
    display: none;
}

/* Note grid inside a cell — N×N sub-grid */
.futoshiki-notes {
    display: grid;
    width: 95%;
    height: 95%;
    pointer-events: none;
}

.futoshiki-notes--size-4 { grid-template-columns: repeat(2, 1fr); grid-template-rows: repeat(2, 1fr); }
.futoshiki-notes--size-5 { grid-template-columns: repeat(3, 1fr); grid-template-rows: repeat(2, 1fr); }
.futoshiki-notes--size-6 { grid-template-columns: repeat(3, 1fr); grid-template-rows: repeat(2, 1fr); }

.futoshiki-note {
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--color-text-secondary, #64748B);
    line-height: 1;
}

/* ─── Constraint slots ─── */
.futoshiki-constraint {
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.75rem;
    line-height: 1;
    color: var(--color-primary, #4F46E5);
    user-select: none;
    pointer-events: none;
    transition: color 0.15s;
}

.futoshiki-constraint--satisfied {
    color: var(--color-success-text, #15803D);
}

.futoshiki-constraint--violated {
    color: var(--color-error-text, #DC2626);
    font-size: 0.85rem;
}

/* ─── Status message below board ─── */
.futoshiki-status {
    font-size: 0.875rem;
    color: var(--color-text-secondary, #64748B);
    text-align: center;
    min-height: 1.25rem;
}