@layer elements {

  /* ── LIBRARY HEADER ──────────────────────────────────────────────────── */
  .library-header {
    padding: 64px 0 40px;
    border-bottom: 1px solid var(--color-rule);
    display: grid;
    grid-template-columns: 1fr auto;
    align-items: end;
    gap: 40px;
  }

  .library-header__label {
    font-family: var(--font-mono);
    font-size: var(--size-xs);
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--color-ink-muted);
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 16px;
  }

  .library-header__label::before {
    content: '';
    display: block;
    width: 32px;
    height: 1px;
    background: var(--color-rule);
  }

  .library-header__title {
    font-size: var(--size-2xl);
    font-weight: 500;
    letter-spacing: -0.02em;
    line-height: var(--leading-tight);
    margin-bottom: 12px;
  }

  .library-header__desc {
    font-size: var(--size-base);
    font-style: italic;
    color: var(--color-ink-mid);
    max-width: 52ch;
  }

  .library-header__right {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 10px;
  }

  .library-header__count {
    font-family: var(--font-mono);
    font-size: var(--size-xs);
    color: var(--color-ink-muted);
    text-align: right;
    line-height: 1.8;
  }

  .library-header__count strong {
    display: block;
    font-size: var(--size-xl);
    font-family: var(--font-body);
    font-weight: 400;
    color: var(--color-ink);
    letter-spacing: -0.02em;
    line-height: 1;
    margin-bottom: 4px;
  }

  /* ── VIEW TOGGLE ─────────────────────────────────────────────────────── */
  .view-toggle {
    display: flex;
    gap: 2px;
  }

  .view-toggle__btn {
    font-family: var(--font-mono);
    font-size: var(--size-xs);
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--color-ink-muted);
    background: var(--color-block-bg);
    border: none;
    padding: 5px 10px;
    cursor: pointer;
    transition: all 0.12s ease;
  }

  .view-toggle__btn:hover { color: var(--color-ink); }
  .view-toggle__btn.active { background: var(--color-ink); color: var(--color-paper); }

  /* ── SHELVES ──────────────────────────────────────────────────────────── */
  .shelves {
    padding: 48px 0 96px;
    display: flex;
    flex-direction: column;
  }

  .shelf { margin-bottom: 48px; }

  .shelf__label {
    font-family: var(--font-mono);
    font-size: var(--size-xs);
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--color-ink-muted);
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 12px;
  }

  .shelf__label::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--color-rule);
  }

  .shelf__row {
    position: relative;
    display: flex;
    align-items: flex-end;
    gap: 4px;
    padding-bottom: 0;
  }

  .shelf__row::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: -8px;
    right: -8px;
    height: 6px;
    background: var(--color-shelf, #C8C0B0);
    border-radius: 1px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.12);
  }

  /* ── SPINE (book on shelf) ───────────────────────────────────────────── */
  .spine {
    height: 200px;
    width: 48px;
    flex-shrink: 0;
    position: relative;
    cursor: pointer;
    margin-bottom: 6px;
  }

  .spine--sm  { width: 36px; }
  .spine--md  { width: 48px; }
  .spine--lg  { width: 60px; }
  .spine--xl  { width: 72px; }

  .spine--short  { height: 160px; }
  .spine--medium { height: 200px; }
  .spine--tall   { height: 230px; }

  .spine__inner {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    transition: transform 0.15s ease, filter 0.15s ease;
    transform-origin: bottom center;
  }

  .spine:hover .spine__inner {
    transform: translateY(-8px);
    filter: brightness(1.04);
  }

  .spine__body {
    width: 100%;
    height: 100%;
    position: relative;
    overflow: hidden;
  }

  .spine__title {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    writing-mode: vertical-rl;
    transform: rotate(180deg);
    font-family: var(--font-body);
    font-size: 11px;
    font-weight: 500;
    color: inherit;
    padding: 8px 4px;
    line-height: 1.2;
    text-align: center;
    overflow: hidden;
    letter-spacing: 0.04em;
  }

  .spine__top {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: rgba(255,255,255,0.2);
  }

  .spine__shadow {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    width: 4px;
    background: rgba(0,0,0,0.15);
  }

  /* ── SPINE TOOLTIP ───────────────────────────────────────────────────── */
  .spine__tooltip {
    position: absolute;
    bottom: calc(100% + 20px);
    left: 50%;
    transform: translateX(-50%);
    width: 200px;
    background: var(--color-ink);
    color: var(--color-paper);
    padding: 14px 16px;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.15s ease;
    z-index: 10;
  }

  .spine__tooltip::after {
    content: '';
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    border: 6px solid transparent;
    border-top-color: var(--color-ink);
  }

  .spine:hover .spine__tooltip,
  .shelf-obj:hover .spine__tooltip { opacity: 1; }

  .spine__tooltip__title {
    font-family: var(--font-body);
    font-size: var(--size-sm);
    font-weight: 500;
    line-height: 1.3;
    margin-bottom: 4px;
  }

  .spine__tooltip__sub {
    font-family: var(--font-mono);
    font-size: 9px;
    letter-spacing: 0.10em;
    text-transform: uppercase;
    color: rgba(244,240,230,0.5);
    margin-bottom: 8px;
  }

  .spine__tooltip__note {
    font-family: var(--font-body);
    font-style: italic;
    font-size: var(--size-xs);
    color: rgba(244,240,230,0.7);
    line-height: 1.55;
    border-top: 1px solid rgba(255,255,255,0.15);
    padding-top: 8px;
  }

  .spine__tooltip__status {
    font-family: var(--font-mono);
    font-size: 9px;
    letter-spacing: 0.10em;
    text-transform: uppercase;
    margin-top: 8px;
    color: #C4562E;
  }

  .spine__tooltip__status--read { color: rgba(244,240,230,0.4); }
  .spine__tooltip__status--ref  { color: rgba(244,240,230,0.6); }

  /* ── SHELF OBJECTS (tools, records) ──────────────────────────────────── */
  .shelf-obj {
    flex-shrink: 0;
    margin-bottom: 6px;
    cursor: pointer;
    position: relative;
  }

  .shelf-obj:hover .shelf-obj__inner { transform: translateY(-8px); }

  .shelf-obj__inner {
    transition: transform 0.15s ease;
    transform-origin: bottom center;
  }

  /* ── VIEW TOGGLE — grid vs shelf ─────────────────────────────────────── */
  .view-grid  { display: none; }
  .view-shelf { display: block; }

  body.view-is-grid .view-grid  { display: block; }
  body.view-is-grid .view-shelf { display: none; }

  /* ── GRID VIEW (catalog) ─────────────────────────────────────────────── */
  .catalog {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2px;
    padding: 2px 0 96px;
  }

  .entry {
    background: var(--color-block-bg);
    padding: 20px 20px 24px;
    display: flex;
    flex-direction: column;
    transition: background 0.12s ease;
  }

  .entry:hover { background: var(--color-block-hover); }

  .entry__header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    margin-bottom: 14px;
  }

  .entry__number {
    font-family: var(--font-mono);
    font-size: var(--size-xs);
    color: var(--color-accent);
    letter-spacing: 0.08em;
  }

  .entry__type {
    font-family: var(--font-mono);
    font-size: 9px;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--color-ink-muted);
    border: 1px solid var(--color-rule);
    padding: 2px 6px;
  }

  .entry__image-placeholder {
    width: 100%;
    aspect-ratio: 4 / 3;
    background: var(--color-rule);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 16px;
    opacity: 0.4;
  }

  .entry__image-placeholder span {
    font-family: var(--font-mono);
    font-size: var(--size-xs);
    color: var(--color-ink-muted);
    letter-spacing: 0.10em;
    text-transform: uppercase;
  }

  .entry__title {
    font-family: var(--font-body);
    font-size: var(--size-base);
    font-weight: 500;
    line-height: 1.3;
    margin-bottom: 4px;
    color: var(--color-ink);
  }

  .entry__byline {
    font-family: var(--font-mono);
    font-size: var(--size-xs);
    color: var(--color-ink-muted);
    letter-spacing: 0.04em;
    margin-bottom: 12px;
  }

  .entry__annotation {
    font-size: var(--size-sm);
    color: var(--color-ink-mid);
    line-height: 1.6;
    margin-top: auto;
    padding-top: 12px;
    border-top: 1px solid var(--color-rule);
  }

  .entry__status {
    font-family: var(--font-mono);
    font-size: 9px;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    margin-top: 12px;
    color: var(--color-ink-muted);
  }

  .entry__status--reading { color: var(--color-accent); }

  /* ── RESPONSIVE ──────────────────────────────────────────────────────── */
  @media (max-width: 768px) {
    .library-header { grid-template-columns: 1fr; }
    .shelf__row { overflow-x: auto; padding-bottom: 8px; }
    .catalog { grid-template-columns: repeat(2, 1fr); }
  }

}