/* Toronto AI — mobile-first, system fonts, editorial */
:root {
  --bg: #fafaf8;
  --surface: #ffffff;
  --text: #1a1a1a;
  --text-muted: #6b6b6b;
  --accent: #2563eb;
  --accent-soft: #eff6ff;
  --border: #e5e5e5;
  --radius: 8px;
  --max-w: 960px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

/* Header */
header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 1.5rem 1rem 1rem;
}
.header-inner { max-width: var(--max-w); margin: 0 auto; }
.site-logo { max-height: 36px; width: auto; }
.site-title {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.02em;
}
.tagline { color: var(--text-muted); font-size: 0.95rem; display: none;}
nav {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}
nav a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-muted);
  padding: 0.25rem 0;
}
nav a:hover { color: var(--accent); text-decoration: none; }

/* Main */
main { max-width: var(--max-w); margin: 0 auto; padding: 1.5rem 1rem 3rem; }
section { margin-bottom: 3rem; }
section h2 {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  letter-spacing: -0.01em;
}
.section-intro { color: var(--text-muted); margin-bottom: 1.25rem; font-size: 0.95rem; }

/* Article cards */
.card-grid { display: grid; gap: 1rem; }
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
}
.card.featured { border-left: 3px solid var(--accent); }
.cat-chip {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 2px 8px;
  border-radius: 999px;
  margin-bottom: 0.5rem;
}
.cat-chip.feed { background: #eff6ff; color: #2563eb; }
.cat-chip.papers { background: #f5f3ff; color: #7c3aed; }
.cat-chip.jobs { background: #ecfdf5; color: #059669; }
.cat-chip.scene { background: #fff7ed; color: #ea580c; }
.card h3 { font-size: 1.1rem; font-weight: 600; line-height: 1.35; }
.card-meta { font-size: 0.8rem; color: var(--text-muted); margin: 0.35rem 0 0.5rem; }
.card-summary { font-size: 0.92rem; color: #444; }
.card-tags { margin-top: 0.75rem; display: flex; gap: 0.4rem; flex-wrap: wrap; }
.tag {
  font-size: 0.72rem;
  background: var(--bg);
  border: 1px solid var(--border);
  padding: 0.1rem 0.45rem;
  border-radius: 4px;
  color: var(--text-muted);
}
.card-author { display: flex; align-items: center; gap: 8px; margin-bottom: 4px; }
.author-avatar { width: 28px; height: 28px; border-radius: 50%; object-fit: cover; flex-shrink: 0; }
.author-name { font-size: 13px; font-weight: 500; color: var(--text-muted, #6b7280); }
.card-link { display: inline-block; margin-top: 0.6rem; font-size: 0.85rem; font-weight: 500; }

/* Filter chips */
.filter-chip {
  display: inline-block;
  padding: 0 18px;
  line-height: 34px;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 500;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-muted);
  cursor: pointer;
  transition: border-color 0.2s, color 0.2s;
}
.filter-chip:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.filter-chip.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

/* Scroll sentinel + empty state */
.scroll-sentinel { height: 1px; }
.empty-state {
  text-align: center;
  padding: 2rem 1rem;
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* Desktop */
@media (min-width: 768px) {
  main { padding: 2rem 1.5rem 4rem; }
  header { padding: 2rem 1.5rem 1.25rem; }
  .site-title { font-size: 2rem; }
}
/* Video hero */
.video-hero {
  max-width: var(--max-w);
  margin: 0 auto;
  position: relative;
  max-height: 600px;
  overflow: hidden;
  transition: max-height 0.5s ease;
}
.video-hero.hero-collapsed {
  max-height: 0;
}
.hero-video {
  width: 100%;
  height: auto;
  display: block;
}
.hero-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 1.5rem;
  background: rgba(0, 0, 0, 0.4);
}
.hero-overlay h1 {
  font-size: 1.75rem;
  font-weight: 700;
  color: #fff;
  max-width: 600px;
  line-height: 1.3;
}
.hero-overlay p {
  color: rgba(255, 255, 255, 0.85);
  margin-top: 0.75rem;
  max-width: 500px;
  font-size: 1rem;
}
.hero-cta {
  display: inline-block;
  margin-top: 1.25rem;
  padding: 0.6rem 1.5rem;
  background: var(--accent);
  color: #fff;
  font-weight: 600;
  font-size: 0.95rem;
  border-radius: var(--radius);
  transition: opacity 0.15s;
}
.hero-cta:hover {
  opacity: 0.85;
  text-decoration: none;
}

/* Nav row */
.nav-row {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  flex-wrap: wrap;
  margin-top: 0.75rem;
}

/* Nav external links */
.nav-links {
  display: flex;
  align-items: center;
  gap: 8px;
}
.nav-link-btn {
  background: linear-gradient(135deg, #ff4870, #eb006a);
  color: #fff;
  border: 1px solid transparent;
  border-radius: 999px;
  padding: 0 18px;
  line-height: 34px;
  font-size: 0.8rem;
  font-weight: 500;
  box-shadow: 2px 6px 15px rgba(255, 72, 112, .35);
  display: inline-block;
  text-decoration: none;
}

/* Hero desktop */
@media (min-width: 768px) {
  .hero-overlay h1 { font-size: 2.2rem; }
  .hero-overlay p { font-size: 1.1rem; }
}