:root {
  --bg: #f6f9fe;
  --hero-bg: #d8e6f7;
  --cream-bg: #fcfcf8;
  --surface: #fbfdff;
  --line: #d3e1f0;
  --line-strong: #b6cde7;
  --text: #1c3550;
  --muted: #617a95;
  --accent: #5d89bb;
  --accent-soft: #e7f0fb;
  --video-radius: 26px;
  --max-width: 1240px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Space Grotesk", "Avenir Next", "Segoe UI", sans-serif;
  color: var(--text);
  background: var(--bg);
}

a {
  color: inherit;
  text-decoration: none;
}

video {
  display: block;
  width: 100%;
  height: auto;
}

.page-shell {
  min-height: 100vh;
}

.upper-shell {
  background: var(--hero-bg);
  border-bottom: 1px solid var(--line);
}

.hero,
.section {
  width: min(calc(100% - 40px), var(--max-width));
  margin: 0 auto;
}

.hero {
  margin-top: 0;
  padding: 22px 0 20px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 0;
}

.topbar__brand {
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
}

.topbar__links {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.topbar__links a {
  color: var(--muted);
  transition: color 180ms ease;
}

.topbar__links a:hover {
  color: var(--text);
}

.hero__content {
  max-width: 1180px;
  padding: 56px 0 0;
  margin: 0 auto;
  text-align: center;
}

.section-tag {
  margin: 0 0 12px;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
}

.hero h1,
.section-heading h2 {
  margin: 0;
  font-family: "Source Serif 4", Georgia, serif;
}

.hero h1 {
  max-width: 1120px;
  margin: 0 auto;
  line-height: 1.01;
}

.hero__title-main,
.hero__title-sub {
  display: block;
}

.hero__title-main {
  font-size: clamp(4rem, 6.2vw, 6.6rem);
}

.hero__title-sub {
  margin-top: 0.18em;
  font-size: clamp(2.15rem, 3.8vw, 3.9rem);
  line-height: 1.06;
}

.hero__authors {
  margin: 18px 0 0;
  font-size: 1.05rem;
  color: var(--muted);
}

.hero__authors-names {
  display: inline-block;
  font-weight: 700;
  margin-bottom: 8px;
}

.hero__actions {
  display: flex;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 20px;
}

.hero__button {
  padding: 11px 18px;
  border: 1px solid rgba(182, 205, 231, 0.9);
  border-radius: 999px;
  background: rgba(251, 253, 255, 0.85);
  color: var(--text);
  font-weight: 500;
  transition: background 180ms ease, border-color 180ms ease;
}

.hero__button:hover {
  background: var(--accent-soft);
  border-color: var(--accent);
}

.hero__lede,
.section-copy,
.intro-copy p,
.comparison-card__caption {
  color: var(--muted);
  line-height: 1.7;
}

.hero__lede {
  max-width: 760px;
  margin: 22px auto 0;
  font-size: 1.08rem;
}

.section {
  padding: 42px 0 18px;
}

.section--intro {
  padding-top: 20px;
  padding-bottom: 40px;
}

.section--abstract {
  width: 100%;
  padding: 0;
  margin: 0;
  background: var(--cream-bg);
  border-top: 1px solid rgba(211, 225, 240, 0.65);
  border-bottom: 1px solid rgba(211, 225, 240, 0.65);
}

.section--abstract .section-heading,
.section--abstract .intro-copy {
  width: min(calc(100% - 40px), var(--max-width));
  margin-left: auto;
  margin-right: auto;
}

.section--abstract .section-heading {
  padding-top: 42px;
}

.section--abstract .intro-copy {
  padding-bottom: 42px;
}

.section-heading {
  margin-bottom: 18px;
}

.section-heading h2 {
  font-size: clamp(2rem, 3vw, 2.9rem);
  line-height: 1.08;
}

.section-copy {
  margin: 14px 0 0;
  max-width: 760px;
}

.intro-copy {
  max-width: 900px;
}

.intro-copy p {
  margin: 0;
  font-size: 1rem;
  text-align: justify;
  text-justify: inter-word;
}

.benchmark-switcher {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin: 24px 0 28px;
}

.benchmark-switcher__button {
  padding: 11px 18px;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  background: var(--surface);
  color: var(--muted);
  font: inherit;
  font-weight: 500;
  cursor: pointer;
  transition: background 180ms ease, color 180ms ease, border-color 180ms ease;
}

.benchmark-switcher__button:hover,
.benchmark-switcher__button.is-active {
  background: var(--accent-soft);
  border-color: var(--accent);
  color: var(--text);
}

.benchmark-panel {
  display: none;
}

.benchmark-panel.is-active {
  display: block;
}

.comparison-grid {
  display: grid;
  gap: 30px;
}

.comparison-card {
  padding: 0 0 30px;
  border-bottom: 1px solid var(--line);
}

.comparison-card__caption {
  margin: 0 0 16px;
  max-width: 900px;
  font-size: 0.98rem;
  font-weight: 700;
  text-align: center;
  margin-left: auto;
  margin-right: auto;
}

.comparison-card__videos {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 22px;
}

.video-panel {
  overflow: hidden;
}

.video-frame {
  position: relative;
  aspect-ratio: 16 / 9;
  background: #dfeaf5;
  border-radius: var(--video-radius);
  overflow: hidden;
}

.video-frame video {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.video-badge {
  position: absolute;
  top: 14px;
  left: 14px;
  z-index: 1;
  padding: 7px 11px;
  border-radius: 999px;
  background: rgba(248, 252, 255, 0.92);
  border: 1px solid rgba(182, 205, 231, 0.9);
  color: var(--text);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.comparison-card.is-visible {
  animation: rise-in 520ms ease both;
}

@keyframes rise-in {
  from {
    opacity: 0;
    transform: translateY(14px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 960px) {
  .comparison-card__videos {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 640px) {
  .hero,
  .section {
    width: min(calc(100% - 24px), var(--max-width));
  }

  .section--abstract .section-heading,
  .section--abstract .intro-copy {
    width: min(calc(100% - 24px), var(--max-width));
  }

  .topbar {
    flex-direction: column;
    align-items: flex-start;
  }

  .hero__content {
    padding-top: 34px;
  }

  .benchmark-switcher {
    gap: 10px;
  }

  :root {
    --video-radius: 20px;
  }
}