:root {
  --bg: #f7f6f3;
  --paper: #ffffff;
  --ink: #1a1d24;
  --muted: #5c6573;
  --line: #e4e2dc;
  --accent: #c94b28;
  --accent-soft: rgba(201, 75, 40, 0.08);
  --font: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --max: 820px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  background:
    linear-gradient(180deg, #efece6 0%, var(--bg) 180px),
    var(--bg);
  line-height: 1.75;
  font-size: 15px;
}

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

a:hover {
  text-decoration: underline;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.85rem clamp(1rem, 4vw, 2rem);
  background: rgba(247, 246, 243, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  color: var(--ink);
  font-weight: 700;
  letter-spacing: 0.08em;
}

.brand:hover {
  text-decoration: none;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 1.75rem;
  height: 1.75rem;
  border: 1px solid var(--accent);
  color: var(--accent);
  font-size: 0.65rem;
  letter-spacing: 0.04em;
}

.topbar-link {
  color: var(--muted);
  font-size: 0.9rem;
}

.page {
  max-width: var(--max);
  margin: 0 auto;
  padding: 2rem clamp(1rem, 4vw, 2rem) 4rem;
}

.doc {
  background: var(--paper);
  border: 1px solid var(--line);
  padding: clamp(1.5rem, 4vw, 2.75rem);
  box-shadow: 0 12px 40px rgba(26, 29, 36, 0.04);
}

.doc-header {
  padding-bottom: 1.5rem;
  margin-bottom: 1.75rem;
  border-bottom: 1px solid var(--line);
}

.doc-header h1 {
  margin: 0 0 0.35rem;
  font-size: clamp(1.6rem, 4vw, 2rem);
  line-height: 1.3;
}

.doc-subtitle {
  margin: 0 0 1.25rem;
  color: var(--muted);
  font-size: 1.05rem;
}

.meta {
  margin: 0;
  display: grid;
  gap: 0.35rem;
  color: var(--muted);
  font-size: 0.92rem;
}

.meta strong {
  color: var(--ink);
  font-weight: 600;
}

.toc {
  margin: 0 0 2rem;
  padding: 1rem 1.1rem;
  background: var(--accent-soft);
  border-left: 3px solid var(--accent);
}

.toc h2 {
  margin: 0 0 0.65rem;
  font-size: 1rem;
}

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

.toc li {
  margin: 0.25rem 0;
}

.toc a {
  color: var(--ink);
}

h2 {
  margin: 2.25rem 0 0.9rem;
  font-size: 1.35rem;
  line-height: 1.4;
  scroll-margin-top: 4.5rem;
}

h3 {
  margin: 1.6rem 0 0.7rem;
  font-size: 1.08rem;
  scroll-margin-top: 4.5rem;
}

h4 {
  margin: 1.25rem 0 0.55rem;
  font-size: 1rem;
}

p {
  margin: 0 0 0.9rem;
}

ul,
ol {
  margin: 0 0 1rem;
  padding-left: 1.35rem;
}

li {
  margin: 0.35rem 0;
}

li > ul,
li > ol {
  margin-top: 0.35rem;
  margin-bottom: 0.35rem;
}

.notice {
  margin: 0 0 1.25rem;
  padding: 1rem 1.1rem;
  background: #f4f1ea;
  border: 1px solid var(--line);
}

.notice p:last-child {
  margin-bottom: 0;
}

.em {
  font-weight: 700;
}

.em-uline {
  font-weight: 700;
  text-decoration: underline;
}

.sdk-block {
  margin: 0.85rem 0 1.1rem;
  padding: 0.9rem 1rem;
  background: #faf9f7;
  border: 1px solid var(--line);
}

.sdk-block p {
  margin-bottom: 0.45rem;
}

.sdk-block p:last-child {
  margin-bottom: 0;
}

.sdk-block a {
  word-break: break-all;
}

.page-footer {
  margin-top: 1.5rem;
  color: var(--muted);
  font-size: 0.85rem;
  text-align: center;
}

@media (max-width: 640px) {
  .doc {
    border-left: 0;
    border-right: 0;
  }
}