.app-topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.6rem 1.25rem;
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--rule);
}

.app-topbar-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.app-brand {
  font-family: var(--serif-display);
  font-weight: 800;
  font-size: 1.15rem;
  letter-spacing: -0.01em;
  color: var(--ink);
  cursor: pointer;
  background: none;
  border: none;
  padding: 0;
}

.reader-layout {
  transition: margin-right 0.5s cubic-bezier(0.22, 1, 0.36, 1);
}
.reader-layout[data-split='true'] {
  margin-right: var(--pdf-w);
}

@media (max-width: 1024px) {
  .reader-layout[data-split='true'] { margin-right: 0; }
}
@media (prefers-reduced-motion: reduce) {
  .reader-layout { transition: none; }
}

.reader { padding-bottom: 4rem; }
.app-footer { margin: 4rem auto 3rem; }

.image-placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  aspect-ratio: 3 / 2;
  width: 100%;
  background: repeating-linear-gradient(
    45deg, var(--exhibit), var(--exhibit) 12px, #f1ece1 12px, #f1ece1 24px
  );
  border: 1px solid var(--rule);
  border-radius: 2px;
  color: var(--ink-soft);
  text-align: center;
  padding: 1rem;
}
.image-placeholder .ph-alt {
  font-family: var(--serif-body);
  font-size: 0.9rem;
  font-style: italic;
  max-width: 32ch;
}

.widget-stub {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--ink-soft);
  text-align: center;
  padding: 2rem;
  letter-spacing: 0.08em;
}