:root {
  --rs-primary: #2563eb;
  --rs-primary-hover: #1d4ed8;
  --rs-dark: #0f172a;
  --rs-surface: #f8fafc;
  --rs-border: #e2e8f0;
  --rs-body-text: #334155;
}

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  color: var(--rs-body-text);
  background-color: var(--rs-surface);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  line-height: 1.7;
}

.font-mono {
  font-family: 'JetBrains Mono', SFMono-Regular, Consolas, monospace;
}

/* Sticky Top Reading Progress Bar */
.reading-progress-container {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: transparent;
  z-index: 1050;
}

.reading-progress-bar {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, #2563eb, #60a5fa);
  box-shadow: 0 0 10px rgba(37, 99, 235, 0.5);
}

/* Navigation Bar */
.main-nav {
  top: 4px; /* Offset for reading progress bar */
}

/* Hero Cover Banner */
.post-hero {
  background: linear-gradient(135deg, rgba(15, 23, 42, 0.94) 0%, rgba(30, 41, 59, 0.88) 100%), url('https://images.unsplash.com/photo-1555066931-4365d14bab8c?auto=format&fit=crop&w=1600&q=80') center/cover no-repeat;
  position: relative;
  padding: 5rem 0 4rem;
  overflow: hidden;
}

.hero-glow-orb {
  position: absolute;
  top: -20%;
  right: 15%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(37, 99, 235, 0.35) 0%, rgba(0,0,0,0) 70%);
  border-radius: 50%;
  pointer-events: none;
  filter: blur(50px);
}

.hero-grid-pattern {
  position: absolute;
  inset: 0;
  background-image: linear-gradient(to right, rgba(255,255,255,0.03) 1px, transparent 1px), linear-gradient(to bottom, rgba(255,255,255,0.03) 1px, transparent 1px);
  background-size: 32px 32px;
  pointer-events: none;
}

/* Article Content Typography & Styling */
.article-content {
  font-size: 1.1rem;
  color: #334155;
}

.article-content p {
  margin-bottom: 1.75rem;
}

.article-content h2 {
  font-weight: 700;
  color: #0f172a;
  margin-top: 3rem;
  margin-bottom: 1.25rem;
  letter-spacing: -0.02em;
}

.article-content h3 {
  font-weight: 600;
  color: #1e293b;
  margin-top: 2rem;
  margin-bottom: 1rem;
}

/* Lead Text Drop Cap */
.article-content p.lead::first-letter {
  font-size: 3.5rem;
  font-weight: 800;
  float: left;
  line-height: 0.8;
  margin-right: 0.75rem;
  margin-top: 0.2rem;
  color: var(--rs-primary);
}

/* Custom Callout Box */
.callout-box {
  background: #eff6ff;
  border-left: 4px solid var(--rs-primary);
  padding: 1.5rem;
  border-radius: 0 0.75rem 0.75rem 0;
  margin: 2rem 0;
}

/* Code Snippet Container */
.code-block {
  background: #0f172a;
  color: #f8fafc;
  border-radius: 0.75rem;
  padding: 1.25rem 1.5rem;
  margin: 2rem 0;
  font-size: 0.925rem;
  box-shadow: 0 10px 25px -5px rgba(15, 23, 42, 0.2);
  border: 1px solid #1e293b;
}

/* Sticky Sidebar Navigation (Table of Contents) */
.sticky-toc {
  position: sticky;
  top: 100px;
}

.toc-link {
  color: #64748b;
  text-decoration: none;
  display: block;
  padding: 0.4rem 0.75rem;
  border-left: 2px solid #e2e8f0;
  font-size: 0.875rem;
  transition: all 0.2s ease;
}

.toc-link:hover, .toc-link.active {
  color: var(--rs-primary);
  border-left-color: var(--rs-primary);
  font-weight: 600;
  background: rgba(37, 99, 235, 0.04);
}

/* Floating Left Social Share Bar */
.floating-share-bar {
  position: fixed;
  left: 2rem;
  top: 50%;
  transform: translateY(-50%);
  z-index: 900;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.share-btn {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: #ffffff;
  border: 1px solid var(--rs-border);
  color: #64748b;
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  box-shadow: 0 4px 12px rgba(0,0,0,0.05);
  transition: all 0.25s ease;
  cursor: pointer;
}

.share-btn:hover {
  background: var(--rs-primary);
  color: #ffffff;
  border-color: var(--rs-primary);
  transform: translateY(-3px);
}

/* Social Platform Grid Tile inside Modal */
.social-tile {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 1rem 0.5rem;
  border-radius: 0.75rem;
  border: 1px solid var(--rs-border);
  color: var(--rs-dark);
  text-decoration: none;
  transition: all 0.2s ease;
  background: #ffffff;
}

.social-tile:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 20px rgba(0,0,0,0.06);
  color: var(--rs-primary);
  border-color: var(--rs-primary);
}

.social-tile i {
  font-size: 1.5rem;
  margin-bottom: 0.4rem;
}

/* QR Code Canvas Frame */
#qrcode-container {
  background: #ffffff;
  padding: 12px;
  border-radius: 12px;
  display: inline-block;
  box-shadow: 0 4px 15px rgba(0,0,0,0.05);
  border: 1px solid var(--rs-border);
}

#qrcode-container img, #qrcode-container canvas {
  display: block;
  margin: 0 auto;
}

/* Author Bio Card */
.author-card {
  background: #ffffff;
  border: 1px solid var(--rs-border);
  border-radius: 1rem;
  padding: 2rem;
}

/* Related Post Cards */
.related-card {
  background: #ffffff;
  border: 1px solid var(--rs-border);
  border-radius: 0.875rem;
  overflow: hidden;
  transition: all 0.25s ease;
}

.related-card:hover {
  border-color: var(--rs-primary);
  box-shadow: 0 15px 30px -10px rgba(15, 23, 42, 0.1);
  transform: translateY(-4px);
}

@media (max-width: 1199px) {
  .floating-share-bar {
    display: none;
  }
}

/* Glassmorphic Navigation Card */
.glass-nav-card {
    background: rgba(18, 24, 38, 0.7);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    transition: border-color 0.4s ease, box-shadow 0.4s ease;
    min-height: 140px;
    will-change: transform;
}

.glass-nav-card:hover {
    border-color: rgba(13, 110, 253, 0.4) !important;
    box-shadow: 0 12px 35px rgba(0, 0, 0, 0.4), 0 0 20px rgba(13, 110, 253, 0.15);
}

/* Background Image & Overlay Effects */
.post-nav-card .card-bg-img {
    background-size: cover;
    background-position: center;
    opacity: 0.15;
    filter: blur(3px) grayscale(40%);
    transition: transform 0.6s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.6s ease, filter 0.6s ease;
    will-change: transform, opacity;
}

.post-nav-card:hover .card-bg-img {
    opacity: 0.35;
    filter: blur(0px) grayscale(0%);
    transform: scale(1.08);
}

.post-nav-card .card-bg-overlay {
    background: linear-gradient(180deg, rgba(15, 23, 42, 0.85) 0%, rgba(15, 23, 42, 0.95) 100%);
    transition: opacity 0.4s ease;
}

/* Typography Line Clamp */
.line-clamp-2 {
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    line-height: 1.4;
}

.tracking-wider {
    letter-spacing: 0.08em;
}