:root {
  --bg: #f6f6f6;
  --paper: #ffffff;
  --text: #222222;
  --muted: #666666;
  --line: #e5e5e5;
  --heading: #111111;
  --link: #1f5aa6;
  --max-width: 960px;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  line-height: 1.85;
}

body {
  padding: 24px 12px 40px;
}

.document {
  width: min(100%, var(--max-width));
  margin: 0 auto;
  background: var(--paper);
  border: 1px solid var(--line);
  padding: 32px 28px 40px;
}

.document h1 {
  margin: 0;
  color: var(--heading);
  font-size: 32px;
  font-weight: 700;
  text-align: center;
  line-height: 1.35;
}

.meta {
  margin-top: 14px;
  color: var(--muted);
  font-size: 14px;
  text-align: center;
}

.intro {
  margin-top: 24px;
  font-size: 15px;
  text-indent: 2em;
}

.section {
  margin-top: 28px;
}

.section h2 {
  margin: 0 0 12px;
  color: var(--heading);
  font-size: 20px;
  font-weight: 700;
  line-height: 1.5;
}

.section h3 {
  margin: 16px 0 8px;
  color: var(--heading);
  font-size: 16px;
  font-weight: 700;
  line-height: 1.6;
}

.section p {
  margin: 10px 0 0;
  font-size: 15px;
  text-indent: 2em;
}

.section ul,
.section ol {
  margin: 10px 0 0 24px;
  padding: 0;
}

.section li {
  margin-top: 8px;
  font-size: 15px;
}

.contact {
  margin-top: 32px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  font-size: 15px;
}

.contact p {
  margin: 8px 0 0;
  text-indent: 0;
}

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

a:hover {
  text-decoration: underline;
}

@media (max-width: 640px) {
  body {
    padding: 12px 8px 24px;
  }

  .document {
    padding: 24px 16px 28px;
  }

  .document h1 {
    font-size: 26px;
  }

  .section h2 {
    font-size: 18px;
  }

  .section h3,
  .section p,
  .section li,
  .contact p {
    font-size: 14px;
  }
}