:root {
  --article-accent: #e53935;
  --article-accent-dark: #c62828;
  --article-accent-soft: #fdecea;
  --article-text: #1f2937;
  --article-muted: #6b7280;
  --article-border: #e5e7eb;
  --article-surface: #f8f9fa;
  --article-card: #ffffff;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: var(--article-border);
  z-index: 10000;
}

.reading-progress-bar {
  height: 100%;
  background: var(--article-accent);
  width: 0%;
  transition: width 0.15s ease;
}

.toc-toggle {
  position: fixed;
  top: max(96px, env(safe-area-inset-top) + 72px);
  right: max(16px, env(safe-area-inset-right));
  background: var(--article-accent);
  color: #fff;
  border: none;
  border-radius: 12px;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  z-index: 1002;
  box-shadow: 0 2px 10px rgba(229, 57, 53, 0.35);
}

.floating-toc {
  position: fixed;
  top: 50%;
  right: 20px;
  transform: translateY(-50%) translateX(12px);
  background: var(--article-card);
  border: 1px solid var(--article-border);
  border-radius: 12px;
  padding: 16px;
  box-shadow: 0 8px 28px rgba(15, 23, 42, 0.12);
  width: min(260px, calc(100vw - 40px));
  max-height: 70vh;
  overflow-y: auto;
  z-index: 1003;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s;
}

body.toc-open .floating-toc {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transform: translateY(-50%) translateX(0);
}

.floating-toc__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 10px;
}

.floating-toc h3 {
  margin: 0;
  font-size: 1rem;
  color: var(--article-text);
}

.floating-toc__close {
  display: none;
  border: none;
  background: transparent;
  color: var(--article-muted);
  font-size: 1.5rem;
  line-height: 1;
  cursor: pointer;
  padding: 0 4px;
}

.floating-toc ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.floating-toc li {
  margin-bottom: 4px;
}

.floating-toc a {
  display: block;
  color: var(--article-muted);
  text-decoration: none;
  font-size: 0.9rem;
  line-height: 1.35;
  padding: 6px 8px;
  border-radius: 6px;
  border-left: 3px solid transparent;
}

.floating-toc a:hover {
  color: var(--article-accent);
  background: var(--article-accent-soft);
}

.floating-toc a.is-active {
  color: var(--article-accent-dark);
  background: var(--article-accent-soft);
  border-left-color: var(--article-accent);
  font-weight: 600;
}

.toc-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.35);
  z-index: 1001;
}

.scroll-to-top {
  position: fixed;
  bottom: max(20px, env(safe-area-inset-bottom));
  right: max(20px, env(safe-area-inset-right));
  background: var(--article-accent);
  color: #fff;
  border: none;
  border-radius: 50%;
  width: 48px;
  height: 48px;
  font-size: 1.2rem;
  cursor: pointer;
  display: none;
  z-index: 1000;
  box-shadow: 0 2px 10px rgba(229, 57, 53, 0.3);
}

.scroll-to-top.show {
  display: block;
}

.related-articles {
  margin: 40px 0 20px;
  padding: 24px;
  background: var(--article-surface);
  border-radius: 10px;
  border: 1px solid var(--article-border);
}

.related-articles h3 {
  margin: 0 0 14px;
  color: var(--article-text);
  font-size: 1.25rem;
}

.related-links {
  list-style: none;
  padding: 0;
  margin: 0;
}

.related-links li {
  margin-bottom: 10px;
}

.related-links a {
  color: var(--article-accent);
  text-decoration: none;
  font-weight: 500;
}

.related-links a:hover {
  text-decoration: underline;
  color: var(--article-accent-dark);
}

.article-content > * {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.article-content > .visible {
  opacity: 1;
  transform: translateY(0);
}

@media (min-width: 1100px) {
  body.has-floating-toc {
    max-width: none;
    padding-right: 300px;
  }

  body.has-floating-toc .toc-toggle,
  body.has-floating-toc .floating-toc__close {
    display: none;
  }

  body.has-floating-toc .floating-toc {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateY(-50%);
  }

  body.has-floating-toc.toc-open .floating-toc {
    transform: translateY(-50%);
  }
}

@media (max-width: 1099px) {
  .floating-toc {
    top: auto;
    bottom: 0;
    right: 0;
    left: 0;
    width: 100%;
    max-height: min(70vh, 520px);
    border-radius: 16px 16px 0 0;
    transform: translateY(110%);
    box-shadow: 0 -8px 28px rgba(15, 23, 42, 0.18);
  }

  body.toc-open .floating-toc {
    transform: translateY(0);
  }

  .floating-toc__close {
    display: inline-flex;
  }
}

[dir="rtl"] .floating-toc {
  right: auto;
  left: 20px;
}

[dir="rtl"] .toc-toggle {
  right: auto;
  left: max(16px, env(safe-area-inset-left));
}

[dir="rtl"] .scroll-to-top {
  right: auto;
  left: max(20px, env(safe-area-inset-left));
}

@media (min-width: 1100px) {
  [dir="rtl"] body.has-floating-toc {
    padding-right: 16px;
    padding-left: 300px;
  }
}

@media (max-width: 1099px) {
  [dir="rtl"] .floating-toc {
    left: 0;
    right: 0;
  }
}