:root {
  color-scheme: light;
  --accent: #2457d6;
  --accent-soft: #e9efff;
  --ink: #15213b;
  --muted: #65708a;
  --line: #dbe2f0;
  --paper: #ffffff;
  --wash: #f4f7fc;
}

* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
}

body {
  background:
    radial-gradient(circle at 12% 8%, rgba(36, 87, 214, 0.12), transparent 30rem),
    linear-gradient(180deg, #f9fbff 0%, var(--wash) 100%);
  color: var(--ink);
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Microsoft YaHei", sans-serif;
  margin: 0;
  min-height: 100vh;
}

main {
  margin: 0 auto;
  max-width: 1120px;
  padding: 88px 28px 56px;
}

.hero {
  max-width: 760px;
}

.eyebrow {
  color: var(--accent);
  display: inline-block;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.16em;
  margin-bottom: 16px;
}

h1,
h2,
p {
  margin-top: 0;
}

h1 {
  font-size: clamp(44px, 8vw, 82px);
  letter-spacing: -0.055em;
  line-height: 1.02;
  margin-bottom: 26px;
}

.lead {
  color: var(--muted);
  font-size: clamp(18px, 2.2vw, 24px);
  line-height: 1.75;
  max-width: 700px;
}

.topics {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin-top: 72px;
}

.topics article {
  background: rgba(255, 255, 255, 0.88);
  border: 1px solid var(--line);
  border-radius: 18px;
  min-height: 220px;
  padding: 26px;
}

.topics article > span {
  background: var(--accent-soft);
  border-radius: 999px;
  color: var(--accent);
  display: inline-grid;
  font-size: 12px;
  font-weight: 800;
  height: 34px;
  place-items: center;
  width: 34px;
}

.topics h2 {
  font-size: 21px;
  margin: 46px 0 12px;
}

.topics p,
.about p {
  color: var(--muted);
  line-height: 1.75;
  margin-bottom: 0;
}

.about {
  align-items: start;
  border-top: 1px solid var(--line);
  display: grid;
  gap: 32px;
  grid-template-columns: minmax(220px, 0.65fr) minmax(0, 1.35fr);
  margin-top: 76px;
  padding-top: 42px;
}

.about h2 {
  font-size: 30px;
  margin-bottom: 0;
}

.about p {
  font-size: 17px;
}

footer {
  align-items: center;
  border-top: 1px solid var(--line);
  color: var(--muted);
  display: flex;
  font-size: 13px;
  gap: 18px;
  justify-content: center;
  margin: 0 auto;
  max-width: 1064px;
  padding: 26px 20px 34px;
}

footer a {
  color: var(--muted);
  text-decoration: none;
}

footer a:hover,
footer a:focus {
  color: var(--accent);
  text-decoration: underline;
}

@media (max-width: 760px) {
  main {
    padding: 58px 18px 42px;
  }

  .topics {
    grid-template-columns: 1fr;
    margin-top: 48px;
  }

  .topics article {
    min-height: 0;
  }

  .topics h2 {
    margin-top: 28px;
  }

  .about {
    grid-template-columns: 1fr;
    margin-top: 56px;
  }

  footer {
    flex-direction: column;
    gap: 8px;
  }
}