:root {
  --fg: #1a1a1a;
  --fg-muted: #555;
  --fg-faint: #888;
  --bg: #ffffff;
  --rule: #e5e5e5;
  --text-width: 760px;
  --wide-width: 1200px;
  --ultrawide-width: 1400px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

main {
  padding: 5rem 1.5rem 4rem;
}

/* Width tiers */
.page-header,
.abstract,
footer {
  max-width: var(--text-width);
  margin-left: auto;
  margin-right: auto;
}

.head-figure,
.figure,
.videos {
  max-width: var(--wide-width);
  margin-left: auto;
  margin-right: auto;
}

.figure--ultrawide {
  max-width: var(--ultrawide-width);
}

/* Header */
.page-header {
  text-align: center;
  margin-bottom: 3rem;
}

.title {
  font-size: 2.5rem;
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.02em;
  margin: 0 0 1.75rem;
  color: var(--fg);
  text-wrap: balance;
}

.authors {
  font-size: 1.05rem;
  color: var(--fg-muted);
  margin: 0.5rem 0;
  font-style: italic;
}

sup {
  font-size: 0.7em;
  color: var(--fg-faint);
}

/* Figures */
.head-figure {
  margin: 3rem auto;
}

.head-figure figure,
.figure figure {
  margin: 0;
}

.head-figure img,
.figure img {
  width: 100%;
  display: block;
  border-radius: 4px;
}

.head-figure figcaption,
.figure figcaption {
  margin-top: 0.85rem;
  font-size: 0.92rem;
  color: var(--fg-muted);
  text-align: left;
  line-height: 1.55;
  max-width: var(--text-width);
  margin-left: auto;
  margin-right: auto;
}

.head-figure figcaption strong,
.figure figcaption strong {
  color: var(--fg);
  font-weight: 600;
}

/* Section common */
section {
  margin: 4rem auto;
}

section h2 {
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  color: var(--fg);
  margin: 0 0 1.25rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--rule);
}

/* Abstract */
.abstract p {
  margin: 0 0 1rem;
  color: var(--fg);
  text-align: justify;
  hyphens: auto;
}

.abstract em {
  font-style: italic;
  font-weight: 500;
}

/* Video grid */
.video-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}

.video-grid figure {
  margin: 0;
}

.video-grid video {
  width: 100%;
  display: block;
  background: #000;
  border-radius: 4px;
}

.video-grid figcaption {
  margin-top: 0.5rem;
  font-size: 0.9rem;
  color: var(--fg-muted);
  text-align: left;
}

/* Footer */
footer {
  margin-top: 5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--rule);
  font-size: 0.85rem;
  color: var(--fg-faint);
  text-align: center;
}

footer p { margin: 0; }

/* Responsive */
@media (max-width: 640px) {
  main {
    padding: 3rem 1.25rem 2.5rem;
  }
  .title {
    font-size: 2rem;
  }
  .video-grid {
    grid-template-columns: 1fr;
    gap: 1.25rem;
  }
  section {
    margin: 2.75rem auto;
  }
}