/* ================================================
   The AI Moment — Main Stylesheet
   ================================================ */

/* --- CSS Custom Properties --- */
:root {
  --color-bg: #0a0e1a;
  --color-bg-secondary: #111827;
  --color-bg-card: #1a2235;
  --color-bg-card-hover: #1e2840;
  --color-surface: #242d40;
  --color-border: #2d3a52;
  --color-text: #e2e8f0;
  --color-text-muted: #94a3b8;
  --color-text-faint: #64748b;
  --color-accent: #60a5fa;
  --color-accent-hover: #93c5fd;
  --color-accent-secondary: #818cf8;
  --color-green: #34d399;
  --color-orange: #f59e0b;
  --color-red: #f87171;
  --color-purple: #a78bfa;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;
  --radius-sm: 4px;
  --radius: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.4);
  --shadow: 0 4px 12px rgba(0,0,0,0.5);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.6);
  --transition: 0.2s ease;
  --max-width: 1100px;
  --container-padding: 1.5rem;
}

/* --- Reset & Base --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* --- Container --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  line-height: 1.3;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 0.75em;
}
h1 { font-size: var(--font-size-4xl); }
h2 { font-size: var(--font-size-3xl); }
h3 { font-size: var(--font-size-2xl); }
h4 { font-size: var(--font-size-xl); }

p { margin-bottom: 1.25em; }

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition);
}
a:hover { color: var(--color-accent-hover); text-decoration: underline; }

ul, ol { padding-left: 1.5em; margin-bottom: 1.25em; }
li { margin-bottom: 0.4em; }

blockquote {
  border-left: 4px solid var(--color-accent);
  margin: 1.5em 0;
  padding: 0.75em 1.25em;
  background: var(--color-bg-card);
  border-radius: 0 var(--radius) var(--radius) 0;
  color: var(--color-text-muted);
  font-style: italic;
}

code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--color-surface);
  padding: 0.15em 0.4em;
  border-radius: var(--radius-sm);
  color: var(--color-accent-secondary);
}

pre {
  background: var(--color-surface);
  padding: 1.25em;
  border-radius: var(--radius);
  overflow-x: auto;
  margin-bottom: 1.5em;
}
pre code { background: none; padding: 0; }

hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 2rem 0;
}

img { max-width: 100%; height: auto; border-radius: var(--radius); }

table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 1.5em;
}
th, td {
  border: 1px solid var(--color-border);
  padding: 0.6em 1em;
  text-align: left;
}
th { background: var(--color-surface); font-weight: 600; }
tr:nth-child(even) { background: var(--color-bg-card); }

/* --- Buttons --- */
.btn {
  display: inline-block;
  padding: 0.65em 1.4em;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: var(--font-size-sm);
  text-decoration: none;
  cursor: pointer;
  transition: all var(--transition);
  border: 2px solid transparent;
}
.btn-primary {
  background: var(--color-accent);
  color: #0a0e1a;
  border-color: var(--color-accent);
}
.btn-primary:hover {
  background: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
  color: #0a0e1a;
  text-decoration: none;
}
.btn-secondary {
  background: transparent;
  color: var(--color-accent);
  border-color: var(--color-accent);
}
.btn-secondary:hover {
  background: var(--color-accent);
  color: #0a0e1a;
  text-decoration: none;
}

/* --- Site Header --- */
.site-header {
  background: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
  padding: 0.85rem 0;
}
.site-header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}
.site-logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  font-size: var(--font-size-xl);
  font-weight: 800;
  color: var(--color-text);
  white-space: nowrap;
}
.site-logo:hover { color: var(--color-accent); text-decoration: none; }
.site-logo-icon { font-size: 1.5rem; }

.site-nav { display: flex; }
.nav-list {
  display: flex;
  list-style: none;
  gap: 0.25rem;
  padding: 0;
  margin: 0;
}
.nav-link {
  display: block;
  padding: 0.45em 0.85em;
  border-radius: var(--radius);
  color: var(--color-text-muted);
  font-weight: 500;
  font-size: var(--font-size-sm);
  transition: all var(--transition);
  text-decoration: none;
}
.nav-link:hover,
.nav-item.active .nav-link {
  color: var(--color-text);
  background: var(--color-surface);
  text-decoration: none;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.nav-toggle-bar {
  width: 24px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: all var(--transition);
}

/* --- Main Content --- */
.main-content {
  flex: 1;
  padding: 3rem 0 4rem;
}

/* --- Hero Section --- */
.hero {
  text-align: center;
  padding: 4rem 0 3rem;
  background: linear-gradient(135deg, var(--color-bg) 0%, var(--color-bg-secondary) 100%);
  border-radius: var(--radius-xl);
  margin-bottom: 3.5rem;
}
.hero-title {
  font-size: clamp(2rem, 5vw, var(--font-size-5xl));
  background: linear-gradient(135deg, var(--color-text) 0%, var(--color-accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 1rem;
}
.hero-description {
  font-size: var(--font-size-xl);
  color: var(--color-text-muted);
  max-width: 640px;
  margin: 0 auto 2rem;
}
.hero-nav { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; }

/* --- Section Headers --- */
.section-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 1.75rem;
}
.section-header h2 { margin-bottom: 0; }
.view-all {
  font-size: var(--font-size-sm);
  color: var(--color-accent);
  white-space: nowrap;
}

/* --- Post Grid --- */
.latest-posts { margin-bottom: 4rem; }
.post-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5rem;
}

.post-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: all var(--transition);
}
.post-card:hover {
  background: var(--color-bg-card-hover);
  border-color: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}
.post-card.has-podcast { border-left: 3px solid var(--color-green); }
.post-card.has-video { border-left: 3px solid var(--color-orange); }

.post-card-body { padding: 1.25rem 1.25rem 0.75rem; flex: 1; }
.post-card-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
  margin-bottom: 0.65rem;
}
.post-date { font-size: var(--font-size-xs); color: var(--color-text-faint); }
.post-card-title {
  font-size: var(--font-size-lg);
  margin-bottom: 0.65rem;
  line-height: 1.4;
}
.post-card-title a { color: var(--color-text); text-decoration: none; }
.post-card-title a:hover { color: var(--color-accent); }
.post-card-excerpt { font-size: var(--font-size-sm); color: var(--color-text-muted); margin-bottom: 0; }

.post-card-footer {
  padding: 0.75rem 1.25rem 1rem;
  border-top: 1px solid var(--color-border);
}
.read-more { font-size: var(--font-size-sm); font-weight: 600; color: var(--color-accent); }
.read-more:hover { color: var(--color-accent-hover); }

/* --- Tags & Badges --- */
.category-tag {
  display: inline-block;
  padding: 0.2em 0.6em;
  background: var(--color-surface);
  color: var(--color-accent-secondary);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  text-decoration: none;
}
.category-tag:hover { background: var(--color-accent-secondary); color: #fff; text-decoration: none; }
.category-tag--small { font-size: 0.65rem; }

.tag {
  display: inline-block;
  padding: 0.15em 0.5em;
  background: var(--color-surface);
  color: var(--color-text-muted);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-xs);
}

.media-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.2em;
  padding: 0.15em 0.55em;
  border-radius: var(--radius-sm);
  font-size: var(--font-size-xs);
  font-weight: 600;
}
.media-badge--podcast { background: rgba(52,211,153,0.15); color: var(--color-green); }
.media-badge--video { background: rgba(245,158,11,0.15); color: var(--color-orange); }

/* --- Topics Grid --- */
.topics { margin-bottom: 3rem; }
.topics h2 { margin-bottom: 1.5rem; }
.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 1.25rem;
}
.topic-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.5rem 1.25rem;
  text-align: center;
  transition: all var(--transition);
  display: block;
  text-decoration: none;
  color: inherit;
  cursor: pointer;
}
.topic-card:hover {
  border-color: var(--color-accent);
  background: var(--color-bg-card-hover);
  transform: translateY(-2px);
}
.topic-icon { font-size: 2rem; margin-bottom: 0.65rem; }
.topic-card h3 { font-size: var(--font-size-base); margin-bottom: 0.5rem; }
.topic-card p { font-size: var(--font-size-xs); color: var(--color-text-muted); margin-bottom: 0; }

/* --- Post (Article) Layout --- */
.post { max-width: 760px; margin: 0 auto; }

.post-header { margin-bottom: 2rem; padding-bottom: 1.5rem; border-bottom: 1px solid var(--color-border); }
.post-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.6rem;
  margin-bottom: 1rem;
}
.post-title { font-size: clamp(1.75rem, 4vw, var(--font-size-4xl)); line-height: 1.25; margin-bottom: 0.65rem; }
.post-subtitle { font-size: var(--font-size-xl); color: var(--color-text-muted); margin-bottom: 0.75rem; }
.post-author { font-size: var(--font-size-sm); color: var(--color-text-muted); }
.post-source { font-size: var(--font-size-sm); color: var(--color-text-muted); }

.post-content h2, .post-content h3, .post-content h4 { margin-top: 2em; }

/* --- Media Embed Sections --- */
.media-embed-section { margin: 2rem 0; }
.media-section-title { font-size: var(--font-size-xl); margin-bottom: 1rem; }

/* --- Podcast Embed --- */
.podcast-embed {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.podcast-embed__player { padding: 0; }
.podcast-embed__badge {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.25rem;
  background: var(--color-surface);
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-green);
  border-bottom: 1px solid var(--color-border);
}
.podcast-embed__badge-icon { font-size: 1.1rem; }
.podcast-embed__iframe {
  width: 100%;
  min-height: 200px;
  border: none;
  display: block;
}
.podcast-embed__link-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1.5rem 1.25rem;
  gap: 1rem;
}
.podcast-embed__link-description {
  margin: 0;
  font-size: var(--font-size-sm);
  color: var(--color-text-faint);
  text-align: center;
}
.podcast-embed__open-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.65rem 1.4rem;
  background: var(--color-green);
  color: #fff;
  border-radius: var(--radius-md);
  font-size: var(--font-size-sm);
  font-weight: 600;
  text-decoration: none;
  transition: opacity 0.15s;
}
.podcast-embed__open-btn:hover { opacity: 0.85; }
.podcast-embed__audio {
  width: 100%;
  padding: 1rem;
  display: block;
}
.podcast-embed__caption {
  padding: 0.65rem 1.25rem;
  font-size: var(--font-size-xs);
  color: var(--color-text-faint);
  text-align: center;
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  margin: 0;
}

/* --- Video Embed --- */
.video-embed { margin: 1.5rem 0; }
.video-embed__container {
  position: relative;
  width: 100%;
  padding-top: 56.25%; /* 16:9 */
  background: var(--color-bg-card);
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--color-border);
}
.video-embed__container--notebooklm { padding-top: 70%; }
.video-embed__badge {
  position: absolute;
  top: 0.75rem;
  left: 0.75rem;
  background: rgba(10,14,26,0.85);
  border-radius: var(--radius-sm);
  padding: 0.3em 0.7em;
  font-size: var(--font-size-xs);
  font-weight: 600;
  color: var(--color-accent);
  z-index: 1;
}
.video-embed__iframe {
  position: absolute;
  top: 0; left: 0;
  width: 100%;
  height: 100%;
  border: none;
}
.video-embed__caption {
  margin-top: 0.5rem;
  font-size: var(--font-size-xs);
  color: var(--color-text-faint);
  text-align: center;
}

/* --- Post Footer --- */
.post-footer { margin-top: 3rem; padding-top: 2rem; border-top: 1px solid var(--color-border); }
.further-reading { margin-bottom: 2rem; }
.further-reading h3 { font-size: var(--font-size-lg); }
.post-navigation {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}
.nav-prev, .nav-next {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-accent);
  max-width: 45%;
}
.nav-next { text-align: right; }

/* --- Page Layout --- */
.page { max-width: 900px; margin: 0 auto; }
.page-header { margin-bottom: 2rem; padding-bottom: 1.5rem; border-bottom: 1px solid var(--color-border); }
.page-title { font-size: clamp(2rem, 4vw, var(--font-size-4xl)); }
.page-subtitle { font-size: var(--font-size-xl); color: var(--color-text-muted); margin-bottom: 0; }

/* --- Article List (used on articles.md, podcasts.md, videos.md) --- */
.article-list { list-style: none; padding: 0; }
.article-list-item {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  margin-bottom: 1.25rem;
  transition: all var(--transition);
}
.article-list-item:hover {
  border-color: var(--color-accent);
  background: var(--color-bg-card-hover);
}
.article-list-item .post-meta { margin-bottom: 0.5rem; }
.article-list-item h3 { font-size: var(--font-size-xl); margin-bottom: 0.5rem; }
.article-list-item h3 a { color: var(--color-text); text-decoration: none; }
.article-list-item h3 a:hover { color: var(--color-accent); }
.article-list-item p { color: var(--color-text-muted); font-size: var(--font-size-sm); margin-bottom: 0.75rem; }

/* --- Filter Bar --- */
.filter-bar {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: 2rem;
}
.filter-btn {
  padding: 0.4em 0.9em;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: transparent;
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
  cursor: pointer;
  transition: all var(--transition);
}
.filter-btn:hover,
.filter-btn.active {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background: rgba(96,165,250,0.1);
}

/* --- Footer --- */
.site-footer {
  background: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  padding: 3rem 0 1.5rem;
  margin-top: auto;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 2.5rem;
  margin-bottom: 2rem;
}
.footer-about h3 { font-size: var(--font-size-lg); margin-bottom: 0.75rem; }
.footer-about p { font-size: var(--font-size-sm); color: var(--color-text-muted); }
.footer-nav h4, .footer-topics h4 { font-size: var(--font-size-sm); text-transform: uppercase; letter-spacing: 0.08em; color: var(--color-text-faint); margin-bottom: 0.75rem; }
.footer-nav ul, .footer-topics ul { list-style: none; padding: 0; }
.footer-nav li, .footer-topics li { margin-bottom: 0.4em; font-size: var(--font-size-sm); color: var(--color-text-muted); }
.footer-nav a { color: var(--color-text-muted); }
.footer-nav a:hover { color: var(--color-accent); }
.footer-bottom {
  padding-top: 1.5rem;
  border-top: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.footer-bottom p { font-size: var(--font-size-xs); color: var(--color-text-faint); margin: 0; }
.rss-link a { color: var(--color-text-faint); }
.rss-link a:hover { color: var(--color-accent); }

/* --- Responsive --- */
@media (max-width: 768px) {
  h1 { font-size: var(--font-size-3xl); }
  h2 { font-size: var(--font-size-2xl); }

  .nav-toggle { display: flex; }

  .site-nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-bg-secondary);
    border-bottom: 1px solid var(--color-border);
    padding: 0.75rem var(--container-padding);
  }
  .site-nav.open { display: flex; }
  .nav-list { flex-direction: column; width: 100%; gap: 0; }
  .nav-link { padding: 0.65em 0.85em; }
  .site-header { position: relative; }

  .hero { padding: 2.5rem var(--container-padding); }
  .hero-nav { flex-direction: column; align-items: center; }

  .post-grid { grid-template-columns: 1fr; }
  .topic-grid { grid-template-columns: repeat(2, 1fr); }

  .footer-grid { grid-template-columns: 1fr; gap: 1.5rem; }
  .footer-bottom { flex-direction: column; text-align: center; }

  .post, .page { max-width: 100%; }
  .post-navigation { flex-direction: column; }
  .nav-prev, .nav-next { max-width: 100%; }
  .nav-next { text-align: left; }
}

@media (max-width: 480px) {
  :root { --container-padding: 1rem; }
  .topic-grid { grid-template-columns: 1fr; }
  .hero-title { font-size: var(--font-size-3xl); }
}

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