:root {
  --bg: #f8fbff;
  --bg-soft: #f3f7ff;
  --card-bg: rgba(255, 255, 255, 0.98);
  --text-1: #152b57;
  --text-2: #5d739b;
  --heading: #112a5f;
  --brand: #1f62ff;
  --brand-2: #3d88ff;
  --border: rgba(31, 98, 255, 0.12);
  --shadow: 0 18px 40px rgba(18, 47, 104, 0.08);
  --shadow-strong: 0 22px 48px rgba(31, 98, 255, 0.1);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  background: linear-gradient(180deg, #f8fbff 0%, #ffffff 42%, #f8fbff 100%);
  color: var(--text-1);
}

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

.container {
  width: min(1180px, calc(100% - 40px));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(31, 98, 255, 0.08);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 64px;
}

.header-nav {
  display: flex;
  gap: 20px;
}

.header-nav a,
.footer-links a {
  color: #17305f;
  font-weight: 600;
}

.header-nav a:hover,
.footer-links a:hover {
  color: var(--brand);
}

.hero {
  padding: 44px 0 30px;
  background:
    radial-gradient(circle at 18% 10%, rgba(31, 98, 255, 0.08), transparent 26%),
    radial-gradient(circle at 82% 16%, rgba(65, 155, 255, 0.1), transparent 28%),
    linear-gradient(180deg, #f8fbff 0%, #eef5ff 100%);
}

.hero-inner {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(360px, 0.9fr);
  gap: 28px;
  align-items: center;
}

.hero-copy h1 {
  margin: 0;
  font-size: clamp(40px, 4.8vw, 58px);
  line-height: 1.08;
  letter-spacing: -0.04em;
  color: #10285a;
}

.hero-copy p {
  margin: 18px 0 0;
  max-width: 620px;
  color: #5a719b;
  font-size: 17px;
  line-height: 1.9;
}

.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 22px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 18px;
  border-radius: 14px;
  font-size: 15px;
  font-weight: 700;
  transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}

.btn:hover {
  transform: translateY(-2px);
}

.btn-primary {
  background: linear-gradient(135deg, var(--brand) 0%, var(--brand-2) 100%);
  color: #fff;
  box-shadow: 0 12px 24px rgba(31, 98, 255, 0.18);
}

.btn-primary:hover,
.btn-secondary:hover {
  box-shadow: 0 22px 44px rgba(18, 47, 104, 0.12);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.76);
  border: 1px solid rgba(31, 98, 255, 0.16);
  color: var(--brand);
}

.hero-visual {
  display: flex;
  align-items: center;
  justify-content: center;
}

.hero-visual img {
  width: 100%;
  max-width: 520px;
  display: block;
  border-radius: 24px;
}

.section {
  padding: 44px 0;
}

.section-soft {
  background: linear-gradient(180deg, rgba(243, 247, 255, 0.92), rgba(255, 255, 255, 0.96));
}

.section-head {
  margin-bottom: 26px;
  text-align: center;
}

.section-head h2 {
  margin: 0;
  color: var(--heading);
  font-size: clamp(28px, 3vw, 38px);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -0.03em;
}

.grid {
  display: grid;
  gap: 16px;
}

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

.card,
.topic,
.about-qr-card {
  border-radius: 22px;
  border: 1px solid var(--border);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.98) 0%, rgba(247, 250, 255, 0.96) 100%);
  box-shadow: var(--shadow);
}

.card,
.topic {
  transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}

.card:hover,
.topic:hover {
  transform: translateY(-2px);
  border-color: rgba(31, 98, 255, 0.18);
  box-shadow: 0 22px 44px rgba(18, 47, 104, 0.12);
}

.card {
  min-height: 220px;
  padding: 20px;
}

.card-mark {
  color: var(--brand);
  font-size: 13px;
  font-weight: 800;
}

.card h3,
.topic h3 {
  margin: 10px 0 8px;
  font-size: 20px;
  font-weight: 800;
  line-height: 1.3;
  color: #162f68;
}

.card p,
.topic p,
.about-copy p {
  margin: 0;
  color: var(--text-2);
  font-size: 15px;
  line-height: 1.85;
}

.topic-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(300px, 0.85fr);
  gap: 16px;
}

.topic-side {
  display: grid;
  gap: 16px;
}

.topic {
  display: flex;
  flex-direction: column;
  min-height: 220px;
  padding: 20px;
}

.topic-feature {
  border-color: rgba(31, 98, 255, 0.18);
  box-shadow: var(--shadow-strong);
}

.topic-badge {
  display: inline-flex;
  align-items: center;
  width: fit-content;
  min-height: 28px;
  padding: 0 10px;
  border-radius: 999px;
  background: rgba(31, 98, 255, 0.1);
  color: var(--brand);
  font-size: 12px;
  font-weight: 700;
}

.topic-badge-muted {
  background: rgba(99, 117, 153, 0.1);
  color: #637599;
}

.topic-preview {
  margin-top: 16px;
  border-radius: 18px;
  overflow: hidden;
  border: 1px solid rgba(31, 98, 255, 0.12);
  background: linear-gradient(180deg, #eff5ff 0%, #ffffff 100%);
}

.topic-preview img {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  object-position: center top;
}

.topic-link {
  margin-top: auto;
  padding-top: 14px;
  color: var(--brand);
  font-size: 14px;
  font-weight: 700;
}

.about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 280px;
  gap: 18px;
  align-items: center;
}

.kicker {
  display: inline-flex;
  align-items: center;
  min-height: 30px;
  padding: 0 12px;
  border-radius: 999px;
  background: rgba(31, 98, 255, 0.08);
  color: var(--brand);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .06em;
  text-transform: uppercase;
}

.about-copy h2 {
  margin: 10px 0 0;
  font-size: clamp(28px, 3vw, 38px);
  line-height: 1.2;
  color: var(--heading);
}

.about-copy p {
  margin-top: 14px;
}

.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 16px;
}

.tag-row span {
  display: inline-flex;
  align-items: center;
  min-height: 36px;
  padding: 0 14px;
  border-radius: 12px;
  border: 1px solid rgba(31, 98, 255, 0.1);
  background: rgba(255, 255, 255, 0.84);
  color: #20407c;
  font-size: 13px;
  font-weight: 700;
}

.about-qr-card {
  padding: 18px;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

.about-qr-card img {
  display: block;
  width: 100%;
  max-width: 170px;
  margin: 0 auto;
  border-radius: 16px;
  background: #fff;
  border: 1px solid rgba(31, 98, 255, 0.1);
}

.about-qr-title {
  margin-top: 14px;
  width: 100%;
  text-align: center;
  color: #17305f;
  font-size: 16px;
  font-weight: 700;
}

.site-footer {
  margin-top: 8px;
  padding: 20px 0;
  background: #101b34;
  color: rgba(255, 255, 255, 0.74);
}

.footer-inner {
  display: flex;
  justify-content: flex-end;
  gap: 20px;
  align-items: center;
}

.footer-links {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
}

@media (max-width: 980px) {
  .hero-inner,
  .grid-3,
  .topic-layout,
  .about-layout,
  .footer-inner {
    grid-template-columns: 1fr;
    display: grid;
  }

  .topic-side {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 760px) {
  .container {
    width: min(1180px, calc(100% - 24px));
  }

  .hero {
    padding: 30px 0 22px;
  }

  .hero-copy h1 {
    font-size: 34px;
  }

  .hero-actions {
    flex-direction: column;
  }

  .btn {
    width: 100%;
  }

  .section {
    padding: 28px 0;
  }

  .about-copy h2 {
    font-size: 26px;
  }
}