/* Article UX — breadcrumbs, progress, related content, series nav */

.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  z-index: 100;
  background: rgba(35, 50, 74, 0.4);
  pointer-events: none;
}

.reading-progress-bar {
  height: 100%;
  width: 0%;
  background: var(--gradient-brand, linear-gradient(90deg, #38bdf8, #60a5fa));
  transition: width 0.1s linear;
  box-shadow: 0 0 8px rgba(56, 189, 248, 0.5);
}

.article-breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  margin-bottom: 14px;
  font-size: 13px;
  color: var(--muted, #94a3b8);
}

.article-breadcrumb a {
  color: var(--cyan, #38bdf8);
  text-decoration: none;
  transition: opacity 0.2s;
}

.article-breadcrumb a:hover {
  opacity: 0.8;
  text-decoration: underline;
}

.article-breadcrumb .sep {
  opacity: 0.4;
}

.article-breadcrumb .crumb-current {
  color: var(--soft, #cbd5e1);
  font-weight: 600;
}

.series-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin: 32px 0 20px;
  padding-top: 24px;
  border-top: 1px solid rgba(56, 189, 248, 0.12);
}

.series-prev,
.series-next {
  flex: 1;
  padding: 14px 16px;
  border: 1px solid rgba(56, 189, 248, 0.15);
  border-radius: var(--radius-md, 14px);
  background: linear-gradient(165deg, rgba(15, 23, 42, 0.7), rgba(15, 23, 42, 0.45));
  color: var(--cyan, #38bdf8);
  font-size: 13px;
  font-weight: 600;
  text-decoration: none;
  transition: all 0.25s ease;
}

.series-next {
  text-align: right;
}

.series-prev:hover,
.series-next:hover {
  border-color: rgba(56, 189, 248, 0.3);
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(56, 189, 248, 0.1);
}

.related-content {
  margin: 32px 0 20px;
  padding: 22px;
  border: 1px solid rgba(56, 189, 248, 0.12);
  border-radius: var(--radius-lg, 20px);
  background: linear-gradient(165deg, rgba(20, 33, 58, 0.6), rgba(10, 17, 31, 0.5));
}

.related-content h2 {
  margin: 0 0 14px;
  font-size: 16px;
  font-weight: 700;
  color: var(--text, #f8fafc);
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 10px;
}

.related-card {
  display: grid;
  gap: 4px;
  padding: 14px;
  border: 1px solid rgba(56, 189, 248, 0.12);
  border-radius: var(--radius-md, 14px);
  background: rgba(15, 23, 42, 0.5);
  text-decoration: none;
  transition: all 0.25s ease;
}

.related-card:hover {
  border-color: rgba(56, 189, 248, 0.28);
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(56, 189, 248, 0.08);
}

.related-card b {
  color: var(--text, #f8fafc);
  font-size: 14px;
}

.related-card span {
  color: var(--muted, #94a3b8);
  font-size: 12px;
  line-height: 1.4;
}

.related-card.related-quiz {
  border-color: rgba(250, 204, 21, 0.25);
  background: linear-gradient(135deg, rgba(250, 204, 21, 0.08), rgba(15, 23, 42, 0.5));
}

.related-card.related-quiz b {
  color: var(--yellow, #facc15);
}

@media (max-width: 600px) {
  .series-nav,
  .chapter-nav-premium {
    flex-direction: column;
    grid-template-columns: 1fr;
  }

  .series-next,
  .chapter-nav-card.next {
    text-align: left;
  }
}

/* Linux series — premium chapter components */
body[data-chapter] .series-nav,
body[data-chapter] .linux-chapter-nav {
  display: none;
}

body[data-chapter] .related-content {
  display: none;
}