:root {
  --bg: #f6f3ee;
  --ink: #1a1a18;
  --muted: #5c5a55;
  --line: #ddd6cb;
  --card: #fffdf9;
  --accent: #2f5d50;
  --accent-soft: #e4efe9;
  --max: 42rem;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "IBM Plex Sans", "Noto Sans SC", "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(1200px 500px at 10% -10%, #e8f0eb 0%, transparent 55%),
    radial-gradient(900px 420px at 100% 0%, #efe6d8 0%, transparent 50%),
    var(--bg);
  line-height: 1.75;
}

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
}

a:hover {
  color: #1f433a;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(10px);
  background: rgba(246, 243, 238, 0.88);
  border-bottom: 1px solid var(--line);
}

.site-header__inner,
.wrap,
.site-footer__inner {
  width: min(100% - 2rem, var(--max));
  margin: 0 auto;
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.85rem 0;
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
  color: inherit;
  text-decoration: none;
}

.brand strong {
  font-family: "IBM Plex Serif", "Noto Serif SC", "Songti SC", serif;
  font-size: 1.15rem;
  letter-spacing: 0.02em;
}

.brand span {
  font-size: 0.75rem;
  color: var(--muted);
}

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  font-size: 0.9rem;
}

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

.nav a:hover,
.nav a.is-active {
  color: var(--accent);
}

main.wrap {
  padding: 2.25rem 0 3.5rem;
}

.hero {
  margin-bottom: 1.75rem;
}

.hero h1 {
  margin: 0 0 0.5rem;
  font-family: "IBM Plex Serif", "Noto Serif SC", "Songti SC", serif;
  font-size: clamp(1.7rem, 4vw, 2.2rem);
  font-weight: 600;
  line-height: 1.25;
  letter-spacing: 0.01em;
}

.meta {
  margin: 0;
  color: var(--muted);
  font-size: 0.92rem;
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 1.4rem 1.35rem 1.6rem;
  box-shadow: 0 10px 30px rgba(40, 35, 25, 0.04);
}

.toc {
  margin: 0 0 1.5rem;
  padding: 1rem 1.1rem;
  background: var(--accent-soft);
  border-radius: 12px;
}

.toc strong {
  display: block;
  margin-bottom: 0.45rem;
}

.toc ol {
  margin: 0;
  padding-left: 1.2rem;
}

.toc a {
  text-decoration: none;
}

article h2 {
  margin: 1.8rem 0 0.65rem;
  padding-top: 0.4rem;
  font-size: 1.15rem;
  scroll-margin-top: 4.5rem;
}

article h2:first-of-type {
  margin-top: 0.4rem;
}

article p,
article li {
  color: #2b2a27;
  font-size: 0.98rem;
}

article ul,
article ol {
  padding-left: 1.2rem;
}

article li + li {
  margin-top: 0.35rem;
}

.note {
  margin-top: 1.75rem;
  padding: 0.95rem 1.05rem;
  border-left: 3px solid var(--accent);
  background: #f3f7f5;
  border-radius: 0 10px 10px 0;
  color: var(--muted);
  font-size: 0.92rem;
}

.site-footer {
  border-top: 1px solid var(--line);
  padding: 1.25rem 0 2rem;
  color: var(--muted);
  font-size: 0.85rem;
}

.site-footer__inner {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.25rem;
  justify-content: space-between;
}

.home-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.35rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.6rem;
  padding: 0.55rem 1.1rem;
  border-radius: 999px;
  border: 1px solid var(--accent);
  font-size: 0.95rem;
  text-decoration: none;
}

.btn-primary {
  background: var(--accent);
  color: #f7fbf9;
}

.btn-primary:hover {
  background: #244a40;
  color: #fff;
}

.btn-ghost {
  background: transparent;
  color: var(--accent);
}

.btn-ghost:hover {
  background: var(--accent-soft);
  color: #1f433a;
}

.feature-list {
  margin: 1.25rem 0 0;
  padding: 0;
  list-style: none;
}

.feature-list li {
  position: relative;
  padding: 0.55rem 0 0.55rem 1.15rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
}

.feature-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 1.05rem;
  width: 0.45rem;
  height: 0.45rem;
  border-radius: 50%;
  background: var(--accent);
}

@media (max-width: 560px) {
  .card {
    padding: 1.15rem 1rem 1.35rem;
  }

  .site-header__inner {
    align-items: flex-start;
    flex-direction: column;
  }
}