:root {
  --bg: #ffffff;
  --text: #0f2942;
  --muted: #5d7186;
  --line: rgba(15, 41, 66, 0.12);
  --surface: #ffffff;
  --brand: #123e67;
  --brand-2: #0f3355;
  --maxw: 1060px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Noto Sans SC", "PingFang SC", sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at 10% -14%, rgba(29, 143, 200, 0.16), transparent 34%),
    radial-gradient(circle at 90% -18%, rgba(18, 62, 103, 0.12), transparent 40%),
    linear-gradient(180deg, #ffffff 0%, #f7fbff 56%, #f4f9ff 100%);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: -1;
  opacity: 0.35;
  background-image:
    linear-gradient(rgba(18, 62, 103, 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(18, 62, 103, 0.06) 1px, transparent 1px);
  background-size: 36px 36px;
  mask-image: radial-gradient(circle at 50% 24%, rgba(0, 0, 0, 0.88), transparent 80%);
}

.container {
  width: min(92vw, var(--maxw));
  margin: 0 auto;
}

.topbar {
  position: sticky;
  top: 10px;
  z-index: 20;
  padding-top: 10px;
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  padding: 10px 14px;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.84);
  backdrop-filter: blur(8px);
  box-shadow: 0 6px 16px rgba(15, 41, 66, 0.06);
}

.brand {
  text-decoration: none;
  color: var(--text);
  font-family: "Manrope", sans-serif;
  font-weight: 800;
  letter-spacing: 0.02em;
}

.nav-links {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.nav-links a {
  text-decoration: none;
  color: var(--muted);
  font-size: 14px;
  font-weight: 700;
  padding: 8px 11px;
  border-radius: 9px;
}

.nav-links a:hover {
  color: var(--text);
  background: rgba(29, 143, 200, 0.14);
}

.hero {
  padding: 62px 0 20px;
}

.hero h1 {
  margin: 0;
  font-family: "Manrope", sans-serif;
  font-size: clamp(26px, 3.7vw, 40px);
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--text);
}

.hero p {
  margin: 14px 0 0;
  color: var(--muted);
  max-width: 60ch;
}

.layout {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  gap: 14px;
  padding-bottom: 40px;
  background: linear-gradient(180deg, rgba(246, 249, 253, 0.94), rgba(246, 249, 253, 0.86));
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 18px;
  box-shadow: 0 10px 24px rgba(15, 41, 66, 0.05);
}

.panel {
  border: 1px solid rgba(15, 41, 66, 0.14);
  border-radius: 16px;
  background: #ffffff;
  box-shadow: 0 10px 20px rgba(15, 41, 66, 0.08);
}

.side {
  position: sticky;
  top: 88px;
  align-self: start;
  padding: 14px;
}

.side h2 {
  margin: 0 0 8px;
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.side a {
  display: block;
  text-decoration: none;
  color: var(--text);
  font-weight: 700;
  padding: 8px 6px;
  border-radius: 8px;
}

.side a:hover {
  background: rgba(10, 120, 206, 0.08);
}

.content {
  padding: 20px;
}

.section {
  margin-bottom: 16px;
  scroll-margin-top: 94px;
}

.section h3 {
  margin: 0 0 10px;
  font-size: clamp(18px, 2vw, 24px);
}

.note {
  margin: 0 0 14px;
  color: var(--muted);
}

.card {
  position: relative;
  border: 1px solid rgba(15, 41, 66, 0.14);
  border-radius: 14px;
  padding: 12px;
  background: linear-gradient(180deg, #ffffff 0%, #f9fcff 100%);
}

.card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  border-radius: 14px 14px 0 0;
  background: linear-gradient(90deg, var(--brand), #1d8fc8);
}

.card + .card {
  margin-top: 10px;
}

.card h4 {
  margin: 0 0 8px;
  font-size: 16px;
}

.cover {
  width: 100%;
  max-width: 680px;
  border-radius: 12px;
  border: 1px solid rgba(15, 41, 66, 0.16);
  display: block;
}

.links {
  margin-top: 10px;
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.links a,
.btn {
  text-decoration: none;
  font-weight: 700;
  font-size: 14px;
  border-radius: 999px;
  padding: 8px 12px;
}

.links a {
  color: var(--brand);
  background: rgba(18, 62, 103, 0.1);
}

.btn {
  color: white;
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
}

.side a.btn {
  color: #ffffff;
  border: 1px solid rgba(255, 255, 255, 0.32);
  text-shadow: 0 1px 1px rgba(0, 0, 0, 0.2);
}

.side a.btn:hover {
  color: #ffffff;
  filter: brightness(1.05);
}

.footer {
  text-align: center;
  color: var(--muted);
  font-size: 13px;
  padding: 16px 0 28px;
}

@media (max-width: 920px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .side {
    position: static;
  }
}