/* ===========================
   Phase 1: Design System Variables
   =========================== */
:root {
  /* Colors — Slate neutral + Blue primary */
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-primary-subtle: #eff6ff;
  --color-bg: #ffffff;
  --color-bg-secondary: #f8fafc;
  --color-surface: #ffffff;
  --color-text: #1e293b;
  --color-text-secondary: #64748b;
  --color-text-muted: #94a3b8;
  --color-border: #e2e8f0;
  --color-border-hover: #cbd5e1;
  --color-star: #f59e0b;
  --color-star-empty: #e2e8f0;
  --color-code-bg: #1e293b;

  /* Fonts */
  --font-sans: 'Pretendard Variable', 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, 'Helvetica Neue', sans-serif;
  --font-serif: 'Noto Serif KR', Georgia, 'Times New Roman', serif;
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;

  /* Layout */
  --container-max: 960px;
  --prose-max: 720px;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.05);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 350ms ease;

  /* Border radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
}

/* ===========================
   Phase 6: Dark Mode Variables
   =========================== */
[data-bs-theme="dark"] {
  --color-primary: #3b82f6;
  --color-primary-hover: #60a5fa;
  --color-primary-subtle: #172554;
  --color-bg: #0f172a;
  --color-bg-secondary: #1e293b;
  --color-surface: #1e293b;
  --color-text: #e2e8f0;
  --color-text-secondary: #94a3b8;
  --color-text-muted: #64748b;
  --color-border: #334155;
  --color-border-hover: #475569;
  --color-star-empty: #475569;
  --color-code-bg: #0f172a;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -4px rgba(0, 0, 0, 0.4);
}

/* ===========================
   Phase 1: Base Styles
   =========================== */
body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background-color: var(--color-bg-secondary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color var(--transition-base), color var(--transition-base);
}

::selection {
  background-color: var(--color-primary);
  color: #ffffff;
}

a {
  color: var(--color-primary);
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-hover);
}

/* Content container — replaces inline max-width */
.content-container {
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: 1rem;
  padding-right: 1rem;
}

/* ===========================
   Phase 2: Site Header
   =========================== */
.site-header {
  background-color: var(--color-bg) !important;
  border-bottom: 1px solid var(--color-border) !important;
  box-shadow: var(--shadow-sm);
  transition: background-color var(--transition-base), border-color var(--transition-base);
}

.site-header .container-fluid {
  max-width: var(--container-max);
}

/* Brand mark + text */
.site-brand {
  display: inline-flex;
  align-items: center;
  gap: 0.625rem;
  text-decoration: none !important;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  border-radius: var(--radius-sm);
  background-color: var(--color-primary);
  color: #ffffff;
  font-weight: 700;
  font-size: 0.75rem;
  letter-spacing: 0.025em;
  flex-shrink: 0;
}

.brand-text {
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--color-text);
}

/* Nav link underline animation */
.site-header .nav-link {
  position: relative;
  color: var(--color-text-secondary) !important;
  font-weight: 500;
  font-size: 0.9375rem;
  padding: 0.5rem 0.125rem !important;
  margin: 0 0.625rem;
  transition: color var(--transition-fast) !important;
}

.site-header .nav-link::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-primary);
  transition: width var(--transition-base);
}

.site-header .nav-link:hover,
.site-header .nav-link.active {
  color: var(--color-primary) !important;
}

.site-header .nav-link:hover::after,
.site-header .nav-link.active::after {
  width: 100%;
}

/* Theme toggle button */
.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: 1rem;
  padding: 0;
}

.theme-toggle:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background-color: var(--color-primary-subtle);
}

/* Dark mode navbar toggler */
[data-bs-theme="dark"] .navbar-toggler-icon {
  filter: invert(1);
}

/* ===========================
   Phase 3: Site Footer
   =========================== */
.site-footer {
  border-top: 1px solid var(--color-border);
  padding: 2rem 0;
  margin-top: 3rem;
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.875rem;
  transition: border-color var(--transition-base);
}

.site-footer p {
  margin: 0 0 0.5rem;
}

.site-footer a {
  color: var(--color-text-muted);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.site-footer a:hover {
  color: var(--color-primary);
}

/* ===========================
   Phase 4: Hero Section
   =========================== */
.hero {
  background: linear-gradient(135deg, var(--color-primary-subtle), var(--color-bg-secondary));
  padding: 4rem 1rem;
  text-align: center;
  margin-bottom: 2rem;
  transition: background var(--transition-base);
}

.hero-title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 800;
  color: var(--color-text);
  margin-bottom: 0.5rem;
  line-height: 1.3;
}

.hero-subtitle {
  font-size: clamp(1rem, 2vw, 1.25rem);
  color: var(--color-text-secondary);
  font-weight: 400;
  margin: 0;
}

/* ===========================
   Phase 4: Post & Review Cards
   =========================== */
.post-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border) !important;
  border-radius: var(--radius-lg) !important;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-base);
  overflow: hidden;
  margin-bottom: 1.25rem;
}

.post-card:hover {
  border-color: var(--color-border-hover) !important;
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.post-card .card-body {
  padding: 1.5rem;
}

.post-card .card-title a {
  text-decoration: none;
  color: var(--color-text);
  transition: color var(--transition-fast);
}

.post-card .card-title a:hover {
  color: var(--color-primary);
}

.post-card .card-text {
  color: var(--color-text-secondary);
}

/* Category badge — pill style */
.badge-category {
  display: inline-block;
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-weight: 500;
  font-size: 0.75rem;
  background-color: var(--color-primary-subtle) !important;
  color: var(--color-primary) !important;
  border: none;
}

/* Line clamp utility */
.line-clamp-3 {
  overflow: hidden;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
}

/* ===========================
   Phase 4: Empty State
   =========================== */
.empty-state {
  text-align: center;
  padding: 4rem 1rem;
  color: var(--color-text-muted);
}

.empty-state-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
  opacity: 0.5;
}

.empty-state-message {
  font-size: 1.125rem;
  margin: 0;
}

/* ===========================
   Star Rating
   =========================== */
.star-rating {
  display: inline-flex;
  gap: 0.25rem;
  font-size: 1.25rem;
}

.star-rating .bi-star-fill {
  color: var(--color-star);
}

.star-rating .bi-star {
  color: var(--color-star-empty);
}

/* Clickable Star Rating (Editor) */
.star-rating-input {
  display: inline-flex;
  gap: 0.25rem;
  font-size: 1.5rem;
}

.star-rating-input .star {
  cursor: pointer;
  color: var(--color-star-empty);
  transition: color var(--transition-fast), transform var(--transition-fast);
  user-select: none;
}

.star-rating-input .star.active {
  color: var(--color-star);
}

.star-rating-input .star:hover {
  transform: scale(1.2);
}

/* ===========================
   Phase 5: Book Review Detail
   =========================== */
.review-header {
  text-align: center;
  padding-bottom: 2rem;
  margin-bottom: 2rem;
  border-bottom: 1px solid var(--color-border);
}

.review-header .badge-category {
  margin-bottom: 0.75rem;
}

.review-header .review-date {
  color: var(--color-text-muted);
  font-size: 0.875rem;
  margin-bottom: 1rem;
}

.review-header h1 {
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
  color: var(--color-text);
}

.review-header .review-author {
  color: var(--color-text-secondary);
  font-size: 1rem;
  margin-bottom: 0.75rem;
}

/* Prose — article body typography */
.prose {
  font-family: var(--font-serif);
  font-size: 1.0625rem;
  line-height: 1.9;
  color: var(--color-text);
  max-width: var(--prose-max);
  margin: 0 auto;
}

.prose p {
  margin-bottom: 1.5rem;
}

.prose h2 {
  font-family: var(--font-sans);
  font-size: 1.5rem;
  font-weight: 700;
  margin-top: 2.5rem;
  margin-bottom: 1rem;
  color: var(--color-text);
}

.prose h3 {
  font-family: var(--font-sans);
  font-size: 1.25rem;
  font-weight: 600;
  margin-top: 2rem;
  margin-bottom: 0.75rem;
  color: var(--color-text);
}

.prose blockquote {
  border-left: 3px solid var(--color-primary);
  background-color: var(--color-primary-subtle);
  padding: 1rem 1.25rem;
  margin: 1.5rem 0;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--color-text-secondary);
}

.prose blockquote p:last-child {
  margin-bottom: 0;
}

.prose code {
  font-family: var(--font-mono);
  background-color: var(--color-bg-secondary);
  padding: 0.125rem 0.375rem;
  border-radius: var(--radius-sm);
  font-size: 0.875em;
  color: var(--color-primary);
}

.prose pre {
  background-color: var(--color-code-bg);
  padding: 1.25rem;
  border-radius: var(--radius-md);
  overflow-x: auto;
  margin: 1.5rem 0;
}

.prose pre code {
  background: none;
  padding: 0;
  color: #e2e8f0;
  font-size: 0.875rem;
  line-height: 1.7;
}

.prose a {
  color: var(--color-primary);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.prose img {
  max-width: 100%;
  border-radius: var(--radius-md);
  margin: 1.5rem 0;
}

.prose ul, .prose ol {
  padding-left: 1.5rem;
  margin-bottom: 1.5rem;
}

.prose li {
  margin-bottom: 0.5rem;
}

/* Back link */
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  color: var(--color-text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  transition: color var(--transition-fast);
}

.back-link:hover {
  color: var(--color-primary);
}

/* ===========================
   Phase 8: Editor Styles
   =========================== */
.section-label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 600;
  font-size: 0.9375rem;
  color: var(--color-text);
  margin-bottom: 1rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--color-border);
}

.section-label i {
  color: var(--color-primary);
}

.editor-textarea {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  line-height: 1.6;
  resize: none;
  min-height: 400px;
  border-top-left-radius: 0 !important;
  border-top-right-radius: 0 !important;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.editor-textarea:focus {
  border-color: var(--color-primary) !important;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15) !important;
}

.preview-area {
  min-height: 400px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1rem;
  overflow-y: auto;
  background-color: var(--color-surface);
  color: var(--color-text);
  transition: border-color var(--transition-base), background-color var(--transition-base);
}

.preview-area h1 { font-size: 1.75rem; margin-top: 1.5rem; margin-bottom: 0.75rem; }
.preview-area h2 { font-size: 1.5rem; margin-top: 1.25rem; margin-bottom: 0.5rem; }
.preview-area h3 { font-size: 1.25rem; margin-top: 1rem; margin-bottom: 0.5rem; }
.preview-area p { margin-bottom: 0.75rem; }
.preview-area blockquote {
  border-left: 3px solid var(--color-primary);
  background-color: var(--color-primary-subtle);
  padding: 0.75rem 1rem;
  color: var(--color-text-secondary);
  margin-bottom: 0.75rem;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}
.preview-area code {
  font-family: var(--font-mono);
  background: var(--color-bg-secondary);
  padding: 0.125rem 0.375rem;
  border-radius: var(--radius-sm);
  font-size: 0.85em;
}
.preview-area pre {
  background: var(--color-code-bg);
  padding: 1rem;
  border-radius: var(--radius-md);
  overflow-x: auto;
}
.preview-area pre code {
  background: none;
  padding: 0;
  color: #e2e8f0;
}

/* Save button */
.btn-save {
  background-color: var(--color-primary);
  color: #ffffff;
  border: none;
  padding: 0.625rem 1.5rem;
  border-radius: var(--radius-md);
  font-weight: 600;
  transition: all var(--transition-fast);
}

.btn-save:hover {
  background-color: var(--color-primary-hover);
  transform: translateY(-1px);
  color: #ffffff;
}

.btn-save:active {
  transform: scale(0.97);
}

/* Book review card pointer */
.book-review-card .card-body {
  cursor: pointer;
}

/* GitHub settings focus */
.github-settings .form-control:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

/* ===========================
   Auth Gate
   =========================== */
.auth-gate-card {
  max-width: 540px;
  margin: 2rem auto;
}

.auth-gate-icon {
  font-size: 2.5rem;
  color: var(--color-text-muted);
}

.auth-gate-icon i {
  color: var(--color-text-muted);
}

/* ===========================
   Editor Toolbar
   =========================== */
.editor-toolbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.25rem;
  padding: 0.5rem;
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-bottom: none;
  border-radius: var(--radius-md) var(--radius-md) 0 0;
}

.toolbar-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-text-secondary);
  font-size: 0.875rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  padding: 0;
}

.toolbar-btn:hover {
  background-color: var(--color-surface);
  color: var(--color-primary);
}

.toolbar-btn:active {
  transform: scale(0.92);
}

.toolbar-divider {
  width: 1px;
  height: 1.25rem;
  background-color: var(--color-border);
  margin: 0 0.25rem;
}

/* ===========================
   Editor Tabs
   =========================== */
.editor-tabs {
  border-bottom: 1px solid var(--color-border);
  margin-bottom: 0;
}

.editor-tabs .nav-link {
  color: var(--color-text-secondary);
  border: 1px solid transparent;
  font-size: 0.875rem;
  font-weight: 500;
  padding: 0.5rem 1rem;
}

.editor-tabs .nav-link:hover {
  color: var(--color-text);
  border-color: transparent;
}

.editor-tabs .nav-link.active {
  color: var(--color-primary);
  background-color: var(--color-surface);
  border-color: var(--color-border) var(--color-border) var(--color-surface);
}

/* ===========================
   Cover Images
   =========================== */
.review-card-cover {
  width: 80px;
  height: 120px;
  object-fit: cover;
  border-radius: var(--radius-sm);
  flex-shrink: 0;
}

.review-card-cover-wrapper {
  width: 80px;
  height: 120px;
}

.review-detail-cover {
  max-height: 200px;
  width: auto;
}

/* ===========================
   Phase 7: Skeleton Loading
   =========================== */
.skeleton {
  background: var(--color-border);
  border-radius: var(--radius-sm);
  position: relative;
  overflow: hidden;
}

.skeleton::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
  animation: skeleton-shimmer 1.5s infinite;
}

[data-bs-theme="dark"] .skeleton::after {
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.05), transparent);
}

@keyframes skeleton-shimmer {
  0% { transform: translateX(-100%); }
  100% { transform: translateX(100%); }
}

.skeleton-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  margin-bottom: 1.25rem;
}

.skeleton-line {
  height: 0.875rem;
  margin-bottom: 0.75rem;
}

.skeleton-line-short { width: 40%; }
.skeleton-line-medium { width: 70%; }
.skeleton-line-long { width: 100%; }
.skeleton-title { height: 1.5rem; width: 60%; margin-bottom: 1rem; }

/* Fade in for loaded content */
.fade-in {
  animation: fadeIn var(--transition-slow) ease forwards;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ===========================
   Phase 9: Micro Interactions
   =========================== */
/* Page entrance animation */
main {
  animation: pageEnter var(--transition-slow) ease;
}

@keyframes pageEnter {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Card stagger animation */
.card-stagger {
  opacity: 0;
  animation: fadeIn var(--transition-slow) ease forwards;
}

/* Button active feedback */
.btn:active {
  transform: scale(0.97);
}

/* Focus visible ring */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

:focus:not(:focus-visible) {
  outline: none;
}

/* ===========================
   Phase 10: Mobile Responsive
   =========================== */
@media (max-width: 767.98px) {
  .hero {
    padding: 2.5rem 1rem;
  }

  .post-card .card-body {
    padding: 1.125rem;
  }

  .prose {
    font-size: 1rem;
  }

  .editor-textarea {
    min-height: 250px;
  }

  .review-header h1 {
    font-size: 1.5rem;
  }

  .review-card-cover {
    width: 60px;
    height: 90px;
  }

  .review-card-cover-wrapper {
    width: 60px;
    height: 90px;
  }

  .review-detail-cover {
    max-height: 150px;
  }

  .toolbar-btn {
    width: 1.75rem;
    height: 1.75rem;
    font-size: 0.8125rem;
  }
}

@media (max-width: 991.98px) {
  .site-header .nav-link::after {
    display: none;
  }

  .site-header .nav-link {
    margin: 0;
    padding: 0.625rem 0 !important;
  }

  .site-header .navbar-nav {
    padding: 0.5rem 0;
  }

  .theme-toggle {
    margin-top: 0.5rem;
    margin-bottom: 0.5rem;
  }
}

/* Touch targets minimum 44px */
@media (pointer: coarse) {
  .nav-link,
  .btn,
  .theme-toggle,
  .star-rating-input .star,
  .filter-chip,
  .btn-scroll-top {
    min-height: 44px;
    min-width: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
  }
}

/* ===========================
   Post Detail (US-01)
   =========================== */
.post-header {
  text-align: center;
  padding-bottom: 2rem;
  margin-bottom: 2rem;
  border-bottom: 1px solid var(--color-border);
}

.post-header h1 {
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
  color: var(--color-text);
}

.post-meta {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 1rem;
  color: var(--color-text-muted);
  font-size: 0.875rem;
  margin-bottom: 1rem;
}

/* ===========================
   Hero Stats (US-02)
   =========================== */
.hero-stats {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.hero-stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.25rem;
}

.hero-stat-number {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1;
}

.hero-stat-label {
  font-size: 0.75rem;
  color: var(--color-text-muted);
  font-weight: 500;
}

.hero-stat-divider {
  width: 1px;
  height: 2rem;
  background-color: var(--color-border);
}

/* Typing cursor */
.typing-cursor {
  display: inline-block;
  width: 2px;
  height: 1em;
  background-color: var(--color-primary);
  margin-left: 2px;
  animation: blink 1s step-end infinite;
  vertical-align: text-bottom;
}

@keyframes blink {
  50% { opacity: 0; }
}

/* ===========================
   Reading Time Badge (US-03)
   =========================== */
.badge-reading-time {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  font-size: 0.75rem;
  color: var(--color-text-muted);
  font-weight: 400;
}

/* ===========================
   Filter/Sort Controls (US-04)
   =========================== */
.filter-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.filter-chips {
  display: flex;
  gap: 0.5rem;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  padding-bottom: 0.25rem;
}

.filter-chips::-webkit-scrollbar {
  display: none;
}

.filter-chip {
  display: inline-flex;
  align-items: center;
  padding: 0.375rem 0.875rem;
  border: 1px solid var(--color-border);
  border-radius: 9999px;
  background-color: var(--color-surface);
  color: var(--color-text-secondary);
  font-size: 0.8125rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.filter-chip:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.filter-chip.active {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
  color: #ffffff;
}

.filter-sort .form-select {
  min-width: 140px;
  font-size: 0.8125rem;
  border-color: var(--color-border);
  color: var(--color-text-secondary);
}

/* ===========================
   Syntax Highlighting Override (US-06)
   =========================== */
.prose pre code.hljs {
  background: none;
  padding: 0;
  font-size: 0.875rem;
  line-height: 1.7;
}

.prose pre:has(code.hljs) {
  background-color: var(--color-code-bg);
}

/* ===========================
   Scroll UI (US-07)
   =========================== */
.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 3px;
  background-color: var(--color-primary);
  z-index: 1031;
  transition: width 50ms linear;
}

.btn-scroll-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 2.75rem;
  height: 2.75rem;
  border-radius: 9999px;
  border: 1px solid var(--color-border);
  background-color: var(--color-surface);
  color: var(--color-text-secondary);
  box-shadow: var(--shadow-md);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.125rem;
  transition: all var(--transition-fast);
  opacity: 0;
  transform: translateY(1rem);
  pointer-events: none;
  z-index: 1020;
}

.btn-scroll-top.visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.btn-scroll-top:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background-color: var(--color-primary-subtle);
}

/* ===========================
   About Page (US-05)
   =========================== */
.about-profile {
  text-align: center;
  padding-bottom: 2rem;
  margin-bottom: 2rem;
  border-bottom: 1px solid var(--color-border);
}

.about-avatar {
  width: 120px;
  height: 120px;
  border-radius: 9999px;
  object-fit: cover;
  margin-bottom: 1rem;
  border: 3px solid var(--color-border);
}

.about-name {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 0.25rem;
}

.about-bio {
  color: var(--color-text-secondary);
  font-size: 1rem;
  margin-bottom: 1rem;
}

.about-social {
  display: flex;
  justify-content: center;
  gap: 0.75rem;
}

.about-social a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 9999px;
  border: 1px solid var(--color-border);
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
  font-size: 1.125rem;
  text-decoration: none;
}

.about-social a:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background-color: var(--color-primary-subtle);
}

.tech-stack {
  margin-top: 2rem;
}

.tech-stack h2 {
  font-family: var(--font-sans);
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--color-text);
}

.tech-badge {
  display: inline-block;
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.8125rem;
  font-weight: 500;
  background-color: var(--color-bg-secondary);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  margin: 0.25rem;
}

/* ===========================
   Footer Extensions (US-09)
   =========================== */
.footer-nav {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  margin-bottom: 1rem;
}

.footer-nav a {
  color: var(--color-text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  transition: color var(--transition-fast);
}

.footer-nav a:hover {
  color: var(--color-primary);
}

.footer-social {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-bottom: 1rem;
}

.footer-social a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  border-radius: 9999px;
  color: var(--color-text-muted);
  transition: color var(--transition-fast);
  font-size: 1.125rem;
  text-decoration: none;
}

.footer-social a:hover {
  color: var(--color-primary);
}

.footer-copyright {
  color: var(--color-text-muted);
  font-size: 0.8125rem;
  margin: 0;
}

/* ===========================
   Additional Mobile Responsive
   =========================== */
@media (max-width: 767.98px) {
  .post-header h1 {
    font-size: 1.5rem;
  }

  .hero-stat-number {
    font-size: 1.25rem;
  }

  .hero-stat-label {
    font-size: 0.6875rem;
  }

  .hero-stats {
    gap: 1rem;
  }

  .filter-bar {
    flex-direction: column;
    align-items: stretch;
  }

  .filter-sort {
    width: 100%;
  }

  .filter-sort .form-select {
    width: 100%;
  }

  .about-avatar {
    width: 100px;
    height: 100px;
  }

  .btn-scroll-top {
    bottom: 1.5rem;
    right: 1.5rem;
  }
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  .typing-cursor {
    animation: none;
  }

  .card-stagger {
    animation: none;
    opacity: 1;
  }

  .fade-in {
    animation: none;
    opacity: 1;
  }

  main {
    animation: none;
  }

  .reading-progress {
    transition: none;
  }
}