/* ══════════════════════════════════════════════════════════════
SOLUTIONS — expandable step-by-step answer blocks
══════════════════════════════════════════════════════════════ */

.solution {
    margin: 0.75rem 0 1rem 0;
    padding: 0.85rem 1.1rem;
    background: var(--bg-tertiary);
    border-left: 3px solid var(--accent);
    border-radius: 6px;
    font-family: var(--font);
    font-size: 1rem;
    line-height: 1.65;
    color: var(--text-body);
}

.solution > summary {
    cursor: pointer;
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 0.9rem;
    color: var(--text-primary);
    letter-spacing: 0.02em;
    text-transform: uppercase;
    list-style: none;
    user-select: none;
    display: flex;
    align-items: center;
    gap: 8px;
}

.solution > summary::-webkit-details-marker { display: none; }

.solution > summary::before {
    content: '▸';
    display: inline-block;
    color: var(--accent);
    font-size: 0.9rem;
    transition: transform 0.15s ease;
}

.solution[open] > summary::before {
    transform: rotate(90deg);
}

.solution[open] > summary {
    margin-bottom: 0.6rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border);
}

.solution p {
    margin: 0.5rem 0;
}

.solution strong {
    color: var(--text-primary);
    font-weight: 600;
}

.solution ol,
.solution ul {
    margin: 0.5rem 0 0.5rem 1.25rem;
    padding-left: 0;
}

.solution li {
    margin-bottom: 0.35rem;
}

.solution .final-answer {
    display: inline-block;
    margin-top: 0.5rem;
    padding: 0.25rem 0.6rem;
    background: var(--accent-bg);
    border-radius: 4px;
    color: var(--text-primary);
    font-weight: 600;
}

.solution .working {
    margin: 0.4rem 0 0.4rem 1rem;
    color: var(--text-secondary);
}

.solution math {
    font-size: 1.05em;
}