.portfolio-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: var(--space-md);
}

.portfolio-filters button {
  padding: 0.6rem 1.3rem;
  border-radius: var(--radius-pill);
  border: 1px solid var(--border-on-dark);
  font-size: var(--fs-sm);
  font-weight: 500;
  transition: background var(--dur-fast) var(--ease-out), border-color var(--dur-fast) var(--ease-out),
    color var(--dur-fast) var(--ease-out);
}
.portfolio-filters button.is-active,
.portfolio-filters button:hover {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--black);
}

.portfolio-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-sm);
  margin-top: var(--space-lg);
}

.portfolio-item {
  cursor: pointer;
}

.portfolio-item[hidden] {
  display: none;
}

.portfolio-item__frame {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-md);
}

.portfolio-item__frame .book-cover {
  transition: transform var(--dur-med) var(--ease-out);
}
.portfolio-item:hover .book-cover {
  transform: scale(1.06);
}

.portfolio-item__overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(to top, rgba(10, 10, 10, 0.9), transparent 60%);
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  padding: var(--space-sm);
  opacity: 0;
  transition: opacity var(--dur-fast) var(--ease-out);
}
.portfolio-item:hover .portfolio-item__overlay {
  opacity: 1;
}

.portfolio-item__overlay span {
  font-size: var(--fs-sm);
  color: var(--cream);
  font-weight: 600;
}
.portfolio-item__overlay small {
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: var(--tracking-wide);
  font-size: 0.7rem;
}

.portfolio-item__caption {
  margin-top: 0.7rem;
}
.portfolio-item__caption strong {
  display: block;
  font-family: var(--font-display);
  font-size: 1rem;
}
.portfolio-item__caption span {
  font-size: var(--fs-sm);
  color: var(--text-on-dark-muted);
}
.section--light .portfolio-item__caption span {
  color: var(--text-on-light-muted);
}
.section--light .portfolio-filters button {
  border-color: var(--border-on-light);
}

/* ---------- Lightbox (intentionally kept dark as a focus-mode overlay,
   independent of the page's light theme) ---------- */
.lightbox {
  position: fixed;
  inset: 0;
  z-index: 5000;
  background: rgba(10, 10, 10, 0.92);
  color: var(--text-on-dark);
  backdrop-filter: blur(6px);
  display: none;
  align-items: center;
  justify-content: center;
  padding: var(--space-md);
}
.lightbox.is-open {
  display: flex;
}

.lightbox__inner {
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: var(--space-lg);
  max-width: 900px;
  width: 100%;
  align-items: center;
}

.lightbox__cover {
  width: 100%;
  max-width: 280px;
  margin-inline: auto;
}

.lightbox__title {
  margin-bottom: 0.6rem;
}
.lightbox__meta {
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: var(--tracking-wide);
  font-size: var(--fs-sm);
  margin-bottom: var(--space-sm);
}
.lightbox__blurb {
  color: var(--text-on-dark-muted);
  max-width: 50ch;
}

.lightbox__close {
  position: absolute;
  top: var(--space-md);
  right: var(--space-md);
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid var(--border-on-dark);
  display: flex;
  align-items: center;
  justify-content: center;
}
.lightbox__close .icon {
  width: 18px;
  height: 18px;
}
.lightbox__close:hover {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--black);
}

@media (max-width: 1024px) {
  .portfolio-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}
@media (max-width: 768px) {
  .portfolio-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .lightbox__inner {
    grid-template-columns: 1fr;
  }
}