:root {
  --paper: #f7f8f4;
  --ink: #11130f;
  --muted: #62685f;
  --line: rgba(17, 19, 15, 0.14);
  --line-strong: rgba(17, 19, 15, 0.28);
  --green: #1f7a4f;
  --red: #bc4b4b;
  --sans: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
  --serif: Georgia, "Times New Roman", "Songti SC", serif;
  --mono: "SFMono-Regular", "JetBrains Mono", "Cascadia Mono", Menlo, monospace;
}

* {
  box-sizing: border-box;
}

html {
  background: var(--paper);
  scroll-padding-top: 96px;
}

body {
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(90deg, rgba(17, 19, 15, 0.035) 1px, transparent 1px),
    linear-gradient(rgba(17, 19, 15, 0.035) 1px, transparent 1px),
    radial-gradient(circle at 82% 10%, rgba(31, 122, 79, 0.09), transparent 28%),
    var(--paper);
  background-size: 56px 56px, 56px 56px, auto, auto;
  font-family: var(--sans);
}

a {
  color: inherit;
  text-decoration-thickness: 1px;
  text-underline-offset: 4px;
}

a:hover {
  color: var(--green);
}

:focus-visible {
  outline: 3px solid var(--green);
  outline-offset: 5px;
}

.skip-link {
  position: absolute;
  z-index: 30;
  top: 10px;
  left: 18px;
  padding: 12px 18px;
  transform: translateY(-160%);
  background: var(--ink);
  color: white;
}

.skip-link:focus {
  transform: translateY(0);
}

.shell {
  width: min(1120px, calc(100% - 36px));
  margin-inline: auto;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid var(--line);
  background: rgba(247, 248, 244, 0.96);
}

.nav {
  min-height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  font-weight: 780;
  text-decoration: none;
}

.mark {
  width: 34px;
  height: 34px;
  flex-shrink: 0;
  position: relative;
  border: 1px solid var(--ink);
  border-radius: 50%;
}

.mark::before,
.mark::after {
  content: "";
  position: absolute;
  inset: 7px 14px;
  border-left: 2px solid var(--green);
  transform: rotate(26deg);
}

.mark::after {
  border-left-color: var(--red);
  transform: rotate(-26deg);
}

.button-link,
.language-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 14px;
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.6);
  font-size: 13px;
  font-weight: 650;
  text-decoration: none;
}

main {
  padding: 64px 0 80px;
}

.article {
  padding: clamp(20px, 4vw, 48px);
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.8);
  box-shadow: 0 24px 80px rgba(38, 47, 39, 0.1);
}

.article-head {
  max-width: 940px;
}

.metadata {
  margin: 0 0 18px;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 12px;
  line-height: 1.6;
}

h1 {
  margin: 0 0 22px;
  font-size: clamp(36px, 5.2vw, 64px);
  line-height: 1.08;
  letter-spacing: -0.035em;
  text-wrap: balance;
}

.deck {
  max-width: 780px;
  margin: 0;
  color: #30352e;
  font-family: var(--serif);
  font-size: clamp(22px, 2.6vw, 29px);
  line-height: 1.5;
}

.language-switcher {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 26px 0;
}

.language-link[aria-current="page"] {
  border-color: var(--ink);
  background: var(--ink);
  color: var(--paper);
}

.visual {
  margin: 0 0 42px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: white;
}

.visual img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: contain;
}

.article-body {
  max-width: 760px;
  margin-inline: auto;
  color: #30352e;
  font-size: 18px;
  line-height: 1.8;
  overflow-wrap: break-word;
}

.article-body p {
  margin: 0 0 22px;
}

.article-body h2 {
  margin: 42px 0 18px;
  color: var(--ink);
  font-size: clamp(24px, 3vw, 31px);
  line-height: 1.3;
  letter-spacing: -0.015em;
}

.article-body strong {
  color: var(--ink);
  font-weight: 700;
}

.article-body ul {
  margin: 0 0 24px;
  padding-left: 26px;
}

.article-body li {
  padding-left: 4px;
  margin-bottom: 12px;
}

.article-body li::marker {
  color: var(--green);
}

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

html[lang="zh-Hans"] h1 {
  line-height: 1.25;
  letter-spacing: 0;
}

html[lang="zh-Hans"] .article-body {
  line-height: 1.95;
}

footer {
  padding: 30px 0 46px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 13px;
  line-height: 1.6;
}

.footer-line {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
}

@media (max-width: 640px) {
  .shell {
    width: calc(100% - 24px);
  }

  main {
    padding: 28px 0 40px;
  }

  .article {
    padding: 20px 18px 28px;
  }

  h1 {
    font-size: clamp(32px, 8.5vw, 46px);
  }

  .deck {
    font-size: 22px;
  }

  .visual {
    margin-bottom: 30px;
  }

  .article-body {
    font-size: 17px;
  }

  .article-body h2 {
    margin-top: 34px;
  }
}

@media print {
  body {
    background: white;
  }

  .topbar,
  .language-switcher,
  .skip-link,
  footer {
    display: none;
  }

  main {
    padding: 0;
  }

  .article {
    width: 100%;
    padding: 0;
    border: 0;
    box-shadow: none;
  }
}