:root {
  --bg: #f5f7fb;
  --surface: #ffffff;
  --text: #17212f;
  --muted: #4e6078;
  --line: #d7dfec;
  --primary: #0f6a8b;
  --accent: #ff7a18;
  --hero-grad: radial-gradient(circle at 20% 20%, #7ad9ff 0%, #f5f7fb 35%),
               radial-gradient(circle at 80% 10%, #ffe1c7 0%, transparent 30%);
  --shadow: 0 12px 30px rgba(23, 33, 47, 0.09);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Manrope', system-ui, -apple-system, sans-serif;
  color: var(--text);
  background: linear-gradient(180deg, #f8fbff 0%, #f4f7fc 100%);
  line-height: 1.6;
  position: relative;
}

body::before,
body::after {
  content: '';
  position: fixed;
  z-index: -1;
  border-radius: 999px;
  pointer-events: none;
  filter: blur(2px);
}

body::before {
  width: 360px;
  height: 360px;
  top: -120px;
  right: -80px;
  background: radial-gradient(circle, rgba(122, 217, 255, 0.26) 0%, rgba(122, 217, 255, 0) 72%);
}

body::after {
  width: 320px;
  height: 320px;
  bottom: -120px;
  left: -80px;
  background: radial-gradient(circle, rgba(255, 176, 124, 0.22) 0%, rgba(255, 176, 124, 0) 72%);
}

h1,
h2,
h3,
.brand {
  font-family: 'Sora', 'Manrope', sans-serif;
  line-height: 1.2;
  margin-top: 0;
}

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

.container {
  width: min(1120px, 92vw);
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(10px);
  background: rgba(245, 247, 251, 0.88);
  border-bottom: 1px solid var(--line);
}

.nav-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 72px;
  gap: 1rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.3px;
  font-size: 2rem;
  line-height: 1;
}

.brand-logo {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  box-shadow: 0 10px 18px rgba(15, 106, 139, 0.25);
  flex-shrink: 0;
}

.brand-text {
  display: inline-block;
}

.site-nav {
  display: flex;
  gap: 1.2rem;
  align-items: center;
}

.site-nav > a,
.dropdown-toggle {
  padding: 0.45rem 0.75rem;
  border-radius: 999px;
  color: var(--muted);
  font-weight: 600;
  border: 0;
  background: transparent;
  font: inherit;
  cursor: pointer;
}

.site-nav > a.active,
.site-nav > a:hover,
.dropdown-toggle.active,
.dropdown-toggle:hover {
  background: #dff3fb;
  color: #064a62;
}

.nav-dropdown {
  position: relative;
}

.dropdown-toggle::after {
  content: '▾';
  margin-left: 0.45rem;
  font-size: 0.8rem;
}

.dropdown-menu {
  display: none;
  position: absolute;
  top: calc(100% + 0.35rem);
  left: 0;
  min-width: 220px;
  padding: 0.45rem;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 12px;
  box-shadow: var(--shadow);
  z-index: 30;
}

.nav-dropdown.open .dropdown-menu {
  display: grid;
  gap: 0.2rem;
}

.dropdown-menu a {
  padding: 0.48rem 0.62rem;
  border-radius: 8px;
  color: var(--muted);
  font-weight: 600;
}

.dropdown-menu a:hover,
.dropdown-menu a.active {
  background: #e8f6ff;
  color: #064a62;
}

.menu-toggle {
  display: none;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--text);
  border-radius: 10px;
  padding: 0.5rem 0.8rem;
  font-weight: 700;
}

.hero {
  background: var(--hero-grad);
  padding: 5.5rem 0 3.5rem;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.3fr 1fr;
  gap: 1.4rem;
  align-items: start;
}

.eyebrow {
  color: var(--primary);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 0.78rem;
  font-weight: 800;
}

.lead {
  font-size: 1.08rem;
  color: var(--muted);
  max-width: 60ch;
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
  margin-top: 1.3rem;
}

.btn {
  display: inline-block;
  padding: 0.74rem 1.1rem;
  border-radius: 10px;
  font-weight: 700;
}

.btn-primary {
  background: linear-gradient(120deg, var(--primary), #0e8da3);
  color: #fff;
}

.btn-ghost {
  border: 1px solid #adc9db;
  color: #0a5670;
  background: #fff;
}

.section {
  padding: 3.2rem 0;
}

.page-top {
  padding-top: 4.5rem;
}

.grid {
  display: grid;
  gap: 1rem;
}

.grid.three {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid.two {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.card {
  background: linear-gradient(160deg, #ffffff 0%, #fbfdff 100%);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 1.15rem;
  box-shadow: var(--shadow);
}

.glow-card {
  background: linear-gradient(165deg, #ffffff, #eef8ff);
}

.card ol,
.card ul {
  padding-left: 1.25rem;
  margin-bottom: 0;
}

.prompt-card pre {
  margin: 0;
  padding: 0.9rem;
  overflow: auto;
  background: #122238;
  color: #d7f1ff;
  border-radius: 12px;
  font-size: 0.86rem;
}

.tool-card ul li,
.timeline-item p {
  color: var(--muted);
}

.video-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

.video-card h2 {
  font-size: 1.08rem;
  margin-bottom: 0.65rem;
}

.video-frame {
  width: 100%;
  aspect-ratio: 16 / 9;
  border: 0;
  border-radius: 12px;
  background: #0f1725;
  display: block;
}

.video-meta {
  margin-top: 0.55rem;
  color: var(--muted);
  font-size: 0.92rem;
}

.timeline {
  display: grid;
  gap: 1rem;
  position: relative;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 18px;
  top: 6px;
  bottom: 6px;
  width: 3px;
  background: linear-gradient(var(--primary), var(--accent));
  border-radius: 10px;
}

.timeline-item {
  padding-left: 2.2rem;
  position: relative;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: 10px;
  top: 22px;
  width: 16px;
  height: 16px;
  background: var(--accent);
  border: 2px solid #fff;
  border-radius: 50%;
}

.site-footer {
  border-top: 1px solid var(--line);
  background: linear-gradient(180deg, #eef4fb 0%, #e8eff9 100%);
  margin-top: 2.8rem;
}

.footer-grid {
  min-height: 92px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  color: #30445d;
  font-size: 0.94rem;
}

.reveal {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

.page-tools .section.page-top,
.page-videos .section.page-top {
  background: linear-gradient(180deg, rgba(223, 243, 251, 0.46) 0%, rgba(245, 247, 251, 0) 100%);
}

.page-scholar .section.page-top,
.page-howto .section.page-top,
.page-howto-codex .section.page-top,
.page-howto-claude .section.page-top {
  background: linear-gradient(180deg, rgba(255, 234, 214, 0.4) 0%, rgba(245, 247, 251, 0) 100%);
}

@media (max-width: 920px) {
  .hero-grid,
  .grid.three,
  .grid.two,
  .video-grid {
    grid-template-columns: 1fr;
  }

  .footer-grid {
    flex-direction: column;
    justify-content: center;
    text-align: center;
    padding: 1rem 0;
  }
}

@media (max-width: 760px) {
  .brand {
    font-size: 1.35rem;
  }

  .brand-logo {
    width: 38px;
    height: 38px;
  }

  .menu-toggle {
    display: inline-block;
  }

  .site-nav {
    position: absolute;
    top: 72px;
    right: 4vw;
    left: 4vw;
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 12px;
    box-shadow: var(--shadow);
    padding: 0.6rem;
    display: none;
    flex-direction: column;
    align-items: stretch;
  }

  .site-nav.open {
    display: flex;
  }

  .nav-dropdown {
    width: 100%;
  }

  .dropdown-toggle {
    width: 100%;
    text-align: left;
  }

  .dropdown-menu {
    position: static;
    min-width: 100%;
    box-shadow: none;
    margin-top: 0.4rem;
    background: #f8fbff;
  }
}