:root {
  --ink: #20242a;
  --muted: #667085;
  --line: #d9dee7;
  --paper: #fffdf8;
  --soft-blue: #eaf3fb;
  --soft-green: #edf6ef;
  --soft-beige: #f5ecdc;
  --soft-pink: #f8ecee;
  --accent: #2f6f8f;
  --accent-dark: #25485e;
  --shadow: 0 18px 50px rgba(38, 45, 56, 0.12);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  color: var(--ink);
  background: #f3f6f8;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans SC", "PingFang SC", Arial, sans-serif;
  line-height: 1.68;
  overflow-x: hidden;
}

figure {
  margin: 0;
}

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

a:hover {
  text-decoration: underline;
}

.shell {
  width: min(1180px, calc(100% - 36px));
  margin: 28px auto 56px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 24px;
  box-shadow: var(--shadow);
  overflow: hidden;
}

.hero {
  padding: 46px 48px 34px;
  border-bottom: 1px solid var(--line);
  background: linear-gradient(180deg, #fffdf9 0%, #f9fbfc 100%);
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--accent-dark);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  line-height: 1.18;
  letter-spacing: 0;
}

h1 {
  margin: 0;
  font-size: clamp(36px, 5vw, 64px);
  overflow-wrap: anywhere;
}

h2 {
  margin: 0 0 14px;
  font-size: 30px;
}

h3 {
  margin: 0 0 8px;
  font-size: 20px;
}

.lead {
  max-width: 820px;
  margin: 18px 0 0;
  color: var(--muted);
  font-size: 19px;
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(320px, 480px);
  gap: 34px;
  align-items: center;
}

.hero-grid > *,
.module-card,
.bilingual > *,
.figure {
  min-width: 0;
}

.hero-image,
.figure {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: white;
  overflow: hidden;
}

.hero-image img,
.figure img {
  display: block;
  width: 100%;
  height: auto;
}

.caption {
  margin: 0;
  padding: 12px 16px 16px;
  color: var(--muted);
  font-size: 14px;
  border-top: 1px solid var(--line);
}

.content {
  padding: 34px 48px 48px;
}

.topnav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 26px;
}

.topnav a,
.pill {
  display: inline-flex;
  align-items: center;
  min-height: 38px;
  padding: 7px 13px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: white;
  color: var(--ink);
  font-size: 14px;
  font-weight: 650;
}

.module-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.module-card,
.panel,
.bilingual,
.summary,
.code-card {
  border: 1px solid var(--line);
  border-radius: 18px;
  background: white;
}

.module-card {
  padding: 20px;
}

.module-card .number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  margin-bottom: 14px;
  border-radius: 50%;
  background: var(--soft-blue);
  color: var(--accent-dark);
  font-weight: 800;
}

.module-card p {
  margin: 0;
  color: var(--muted);
}

.section {
  margin-top: 34px;
}

.bilingual {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0;
  overflow: hidden;
}

.zh,
.en {
  padding: 24px;
}

.zh {
  background: white;
  border-right: 1px solid var(--line);
}

.en {
  background: #fbfcfd;
}

.lang-label {
  display: inline-block;
  margin-bottom: 10px;
  color: var(--accent-dark);
  font-size: 13px;
  font-weight: 800;
}

.key-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  padding: 0;
  list-style: none;
}

.key-list li {
  min-height: 72px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--soft-green);
}

.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: white;
}

table {
  width: 100%;
  border-collapse: collapse;
  min-width: 720px;
}

th,
td {
  padding: 14px 16px;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

th {
  background: var(--soft-blue);
  font-size: 14px;
}

tr:last-child td {
  border-bottom: 0;
}

pre {
  margin: 0;
  padding: 18px;
  overflow-x: auto;
  color: #123;
  background: #f6f8fa;
  border-radius: 16px;
}

code {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 0.92em;
}

.summary {
  padding: 22px 24px;
  background: var(--soft-beige);
}

.summary p {
  margin: 0;
  font-size: 19px;
  font-weight: 700;
}

.pager {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  margin-top: 36px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.pager a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 10px 16px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: white;
  color: var(--ink);
  font-weight: 700;
}

.callout {
  padding: 18px 20px;
  border: 1px solid #dce8d9;
  border-radius: 16px;
  background: var(--soft-green);
}

.course-map {
  margin: 0;
  padding-left: 24px;
  font-size: 24px;
}

.course-map li {
  margin: 8px 0;
}

@media (max-width: 900px) {
  .shell {
    width: min(100% - 20px, 760px);
    margin: 10px auto 32px;
    border-radius: 18px;
  }

  .hero,
  .content {
    padding: 28px 22px;
  }

  .hero-grid,
  .bilingual,
  .module-grid,
  .key-list {
    grid-template-columns: 1fr;
  }

  .hero-grid {
    display: block;
  }

  .hero-image {
    margin-top: 24px;
  }

  .zh {
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  h1 {
    font-size: 38px;
  }
}

@media (max-width: 560px) {
  .shell {
    width: 100vw;
    max-width: 100vw;
    margin: 0;
    border-left: 0;
    border-right: 0;
    border-radius: 0;
  }

  .hero,
  .content {
    width: 100%;
    max-width: 100%;
    padding: 24px 16px;
    overflow-x: hidden;
  }

  .lead,
  .topnav,
  .hero-image,
  .figure,
  .module-grid,
  .summary,
  .bilingual,
  .table-wrap,
  .code-card,
  .key-list,
  .pager {
    width: 100%;
    max-width: 100%;
    overflow-x: hidden;
  }

  .hero-image img,
  .figure img {
    width: 100%;
    max-width: 100%;
    object-fit: contain;
  }

  h1 {
    font-size: 32px;
  }

  .lead {
    font-size: 17px;
  }
}