.book-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(145px, 1fr));
    gap: 0.5rem;
}

.book-tile {
    background-color: var(--color-bg-elevated);
    border: 1px solid var(--color-border);
    color: var(--color-text-primary);
    padding: 16px 0;
    text-align: center;
    border-radius: 6px;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.2s;
    font-size: 1rem;
}

/* 타일은 링크다(크롤러가 따라간다) — 버튼이던 때와 같게 보이도록 */
a.book-tile {
    display: block;
    text-decoration: none;
}

.book-tile:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

@media (hover: hover) and (pointer: fine) {
    .book-tile:hover {
        background-color: var(--color-border);
    }
}

.book-sections {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.book-section {
    background: var(--color-bg-elevated-bright);
    border: 1px solid var(--color-border);
    border-radius: 12px;
    padding: 1rem 1rem 1.25rem;
    box-shadow: 0 8px 24px var(--color-shadow);
}

.book-section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    margin-bottom: 0.75rem;
    width: 100%;
    background: none;
    border: none;
    padding: 0;
    cursor: pointer;
    font: inherit;
    color: inherit;
    text-align: left;
}

@media (hover: hover) and (pointer: fine) {
    .book-section-header:hover .book-section-title {
        color: var(--color-accent);
    }
}

.book-section-header[aria-expanded="false"] {
    margin-bottom: 0;
}

.book-section-header-left {
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.book-section-chevron {
    width: 1.25rem;
    height: 1.25rem;
    color: var(--color-text-secondary);
    transition: transform 0.25s ease;
    flex-shrink: 0;
}

.book-section-header[aria-expanded="false"] .book-section-chevron {
    transform: rotate(-90deg);
}

.book-section-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin: 0;
    color: var(--color-text-primary);
    transition: color 0.2s;
}

.book-section-count {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    background-color: var(--color-bg-base);
    padding: 0.2rem 0.65rem;
    border-radius: 999px;
    border: 1px solid var(--color-border);
}

.book-section-body {
    overflow: hidden;
    transition: grid-template-rows 0.3s ease;
}

.book-section-body.collapsed {
    display: none;
}