:root {
  color-scheme: light;
  --bg: #fff;
  --soft: #f8f9fc;
  --ink: #30364a;
  --muted: #606b80;
  --border: #e5e8f0;
  --accent: #584bd9;
}

* {
  box-sizing: border-box;
}
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: Inter, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}
a {
  color: var(--accent);
  text-decoration: none;
}
a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 5px;
}
header {
  max-width: 1140px;
  min-height: 108px;
  padding: 24px 36px;
  margin: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--ink);
  font-size: 22px;
  font-weight: 650;
}
.brand img {
  object-fit: contain;
}
.brand small {
  display: block;
  margin-top: 2px;
  font-size: 8px;
  letter-spacing: 2px;
  color: var(--muted);
}
.back {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 16px;
  font-size: 13px;
}
main {
  max-width: 900px;
  margin: 36px auto 80px;
  padding: 44px 52px;
  border: 1px solid var(--border);
  border-radius: 14px;
  font-size: 15px;
  line-height: 1.95;
  overflow-wrap: anywhere;
}
h1 {
  margin: 0 0 28px;
  font-size: 28px;
  line-height: 1.5;
  letter-spacing: -0.5px;
}
h2 {
  margin: 36px 0 14px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  font-size: 21px;
}
h3 {
  margin: 24px 0 12px;
  font-size: 17px;
}
p {
  margin: 12px 0;
}
li {
  margin: 8px 0;
}
@media (prefers-color-scheme: dark) {
  :root {
    color-scheme: dark;
    --bg: #111624;
    --soft: #191f30;
    --ink: #e1e3ed;
    --muted: #969fb4;
    --border: #2b334a;
    --accent: #aaa0f6;
  }
}
@media (max-width: 600px) {
  header {
    min-height: 100px;
    padding: 24px 22px;
  }
  main {
    margin: 12px 20px 40px;
    padding: 26px 22px;
    font-size: 14px;
  }
  h1 {
    font-size: 24px;
  }
}