:root {
  --paper: #ffffff;
  --ink: #111110;
  --body: #4e4e47;
  --muted: #6b6b63;
  --line: #e2e0da;
  --red: #c8102e;
  --soft: #f7f5f0;
  --sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --serif: "Songti SC", "Noto Serif SC", "Source Han Serif SC", SimSun, Georgia, serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration-thickness: 1px; text-underline-offset: 3px; }

.mast {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 24px;
  max-width: 1160px;
  margin: 0 auto;
  padding: 28px 28px 18px;
  border-bottom: 1px solid var(--line);
}

.brand { text-decoration: none; display: flex; align-items: baseline; gap: 10px; }
.brand-cn { font-family: var(--serif); font-size: 28px; font-weight: 600; letter-spacing: 0.08em; }
.brand-sub { color: var(--muted); font-size: 12px; letter-spacing: 0.06em; }

.mast-nav { display: flex; flex-wrap: wrap; gap: 18px; font-size: 13px; color: var(--body); }
.mast-nav a { text-decoration: none; }
.mast-nav a:hover { color: var(--ink); }
.mast-gh { color: var(--red); }

main { max-width: 1160px; margin: 0 auto; padding: 0 28px 40px; }

.hero { padding: 64px 0 56px; border-bottom: 1px solid var(--line); }
.hero-copy { max-width: 880px; }
.hero-visual { margin: 34px 0 0; }
.hero-visual a { display: block; border: 1px solid var(--line); padding: 10px; background: var(--soft); }
.hero-visual img { display: block; width: 100%; height: auto; }
.hero-visual figcaption { margin-top: 10px; color: var(--muted); font-size: 12px; line-height: 1.6; }
.eyebrow {
  margin: 0 0 18px;
  color: var(--red);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}
.hero h1 {
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(34px, 5vw, 58px);
  font-weight: 600;
  line-height: 1.22;
  letter-spacing: -0.01em;
}
.lede {
  max-width: 780px;
  margin: 26px 0 0;
  color: var(--body);
  font-size: 17px;
}
.hero-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 30px; }

.btn {
  display: inline-block;
  padding: 10px 16px;
  background: var(--ink);
  color: var(--paper);
  border: 1px solid var(--ink);
  font-size: 13px;
  font-weight: 600;
  text-decoration: none;
}
.btn:hover { background: var(--red); border-color: var(--red); }
.btn-ghost { background: transparent; color: var(--ink); }
.btn-ghost:hover { background: var(--ink); color: var(--paper); border-color: var(--ink); }

.note { margin: 18px 0 0; color: var(--muted); font-size: 12.5px; }

.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 20px;
  padding: 56px 0 20px;
  border-bottom: 1px solid var(--line);
}
.section-head h2 { margin: 0; font-family: var(--serif); font-size: 28px; font-weight: 600; }
.section-head p { margin: 0; color: var(--muted); font-size: 12.5px; }

.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0;
  border-bottom: 1px solid var(--line);
}
.tab {
  appearance: none;
  background: transparent;
  border: 0;
  border-bottom: 2px solid transparent;
  padding: 12px 14px;
  color: var(--muted);
  font: inherit;
  font-size: 13px;
  cursor: pointer;
}
.tab:hover { color: var(--ink); }
.tab.is-active { color: var(--ink); border-bottom-color: var(--red); font-weight: 600; }

.frame {
  margin-top: 20px;
  padding: 12px;
  background: var(--soft);
  border: 1px solid var(--line);
}
.frame a { display: block; }
.frame img { display: block; width: 100%; height: auto; }
.frame.is-mobile { max-width: 420px; margin-left: auto; margin-right: auto; }

.viewer-meta {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 2px 0;
  color: var(--muted);
  font-size: 12.5px;
}
.viewer-meta p { margin: 0; }
.viewer-meta a { color: var(--red); }

.feature-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  border-left: 1px solid var(--line);
}
.feature {
  padding: 24px 22px 28px;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.feature-no { margin: 0 0 12px; color: var(--red); font-size: 11px; letter-spacing: 0.12em; }
.feature h3 { margin: 0 0 10px; font-family: var(--serif); font-size: 20px; font-weight: 600; }
.feature p:last-child { margin: 0; color: var(--body); font-size: 13.5px; }

.diy {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 60px;
  margin-top: 56px;
  padding: 42px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.diy .eyebrow { margin-bottom: 12px; }
.diy h2 { margin: 0 0 14px; font-family: var(--serif); font-size: 32px; font-weight: 600; }
.diy-lede { margin: 0 0 22px; color: var(--body); }
.diy-list { align-self: end; }
.diy-list p { display: flex; justify-content: space-between; gap: 20px; margin: 0; padding: 11px 0; border-bottom: 1px solid var(--line); font-size: 13px; }
.diy-list span { color: var(--muted); }

.status { padding: 28px 0 12px; color: var(--muted); font-size: 13px; }
.status p { margin: 0; max-width: 800px; }
.status strong { color: var(--ink); }

.foot {
  display: flex;
  justify-content: space-between;
  gap: 24px;
  max-width: 1160px;
  margin: 0 auto;
  padding: 22px 28px 48px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 12px;
}
.foot p { margin: 0; }
.foot a { text-decoration: none; }
.foot a:hover { color: var(--ink); }
.foot span { margin: 0 6px; }

@media (max-width: 860px) {
  .mast { align-items: flex-start; flex-direction: column; }
  .hero { padding-top: 48px; }
  .section-head { align-items: flex-start; flex-direction: column; gap: 4px; }
  .feature-grid { grid-template-columns: repeat(2, 1fr); }
  .diy { grid-template-columns: 1fr; gap: 28px; }
  .foot { flex-direction: column; }
}

@media (max-width: 560px) {
  .mast, main, .foot { padding-left: 18px; padding-right: 18px; }
  .brand-cn { font-size: 24px; }
  .brand-sub { display: none; }
  .hero h1 br { display: none; }
  .feature-grid { grid-template-columns: 1fr; }
  .viewer-meta { flex-direction: column; gap: 6px; }
  .tabs { overflow-x: auto; flex-wrap: nowrap; }
  .tab { white-space: nowrap; }
}