:root {
  --ink: #17211c;
  --muted: #5d6a63;
  --paper: #f5f3ec;
  --card: #fffefa;
  --line: #dcded7;
  --green: #174b3a;
  --green-soft: #e0ede6;
  --gold: #a96f22;
  --gold-soft: #f7ead7;
  --red: #9b3b32;
  --red-soft: #f7e5e1;
  --shadow: 0 14px 36px rgba(23, 33, 28, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 15% 12%, rgba(23, 75, 58, 0.08), transparent 28rem),
    var(--paper);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    "PingFang SC", "Microsoft YaHei", sans-serif;
  line-height: 1.65;
}

a {
  color: inherit;
}

.hero {
  color: #f7f5ed;
  background:
    linear-gradient(115deg, rgba(4, 30, 22, 0.96), rgba(23, 75, 58, 0.88)),
    repeating-linear-gradient(
      45deg,
      transparent,
      transparent 22px,
      rgba(255, 255, 255, 0.025) 22px,
      rgba(255, 255, 255, 0.025) 23px
    );
  border-bottom: 4px solid #c99a51;
}

.hero__inner {
  width: min(1180px, calc(100% - 40px));
  margin: 0 auto;
  padding: 76px 0 54px;
}

.eyebrow,
.kicker {
  margin: 0 0 8px;
  color: #c99a51;
  font-size: 0.76rem;
  font-weight: 800;
  letter-spacing: 0.16em;
}

.hero h1 {
  max-width: 760px;
  margin: 0;
  font-family: Georgia, "Songti SC", serif;
  font-size: clamp(2.6rem, 7vw, 5.6rem);
  font-weight: 500;
  letter-spacing: -0.045em;
  line-height: 1.02;
}

.hero__lead {
  max-width: 720px;
  margin: 22px 0 28px;
  color: #dbe5df;
  font-size: 1.12rem;
}

.hero__notice {
  max-width: 820px;
  padding: 16px 18px;
  color: #efe8d8;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 12px;
}

.layout {
  display: grid;
  grid-template-columns: 245px minmax(0, 1fr);
  gap: 46px;
  width: min(1180px, calc(100% - 40px));
  margin: 46px auto 70px;
}

.sidebar__sticky {
  position: sticky;
  top: 24px;
}

.search span {
  display: block;
  margin-bottom: 7px;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 700;
}

.search input {
  width: 100%;
  padding: 12px 14px;
  color: var(--ink);
  background: rgba(255, 254, 250, 0.88);
  border: 1px solid var(--line);
  border-radius: 10px;
  font: inherit;
  outline: none;
}

.search input:focus {
  border-color: var(--green);
  box-shadow: 0 0 0 3px rgba(23, 75, 58, 0.12);
}

.section-nav {
  display: grid;
  gap: 4px;
  margin: 22px 0;
}

.section-nav a {
  display: flex;
  justify-content: space-between;
  padding: 8px 10px;
  color: var(--muted);
  border-radius: 8px;
  text-decoration: none;
}

.section-nav a:hover {
  color: var(--green);
  background: var(--green-soft);
}

.section-nav small {
  color: #8b948f;
}

.glossary-link {
  color: var(--green);
  font-size: 0.9rem;
  font-weight: 750;
  text-decoration: none;
}

.content {
  min-width: 0;
}

.start-card {
  display: grid;
  grid-template-columns: minmax(220px, 0.8fr) 1.2fr;
  gap: 30px;
  padding: 30px 34px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 18px;
  box-shadow: var(--shadow);
}

.start-card h2,
.section-heading h2,
.checklist h2 {
  margin: 0;
  font-family: Georgia, "Songti SC", serif;
  font-size: clamp(1.7rem, 3vw, 2.45rem);
  font-weight: 500;
  line-height: 1.2;
}

.start-card ol {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px 28px;
  margin: 0;
  padding-left: 24px;
}

.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  margin: 26px 0 48px;
  color: var(--muted);
  font-size: 0.86rem;
}

.dot {
  display: inline-block;
  width: 9px;
  height: 9px;
  margin-right: 6px;
  border-radius: 99px;
}

.dot--core {
  background: var(--green);
}

.dot--later {
  background: var(--gold);
}

.dot--advanced {
  background: var(--red);
}

.manual-section {
  margin: 0 0 58px;
  scroll-margin-top: 20px;
}

.section-heading {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: end;
  gap: 20px;
  margin-bottom: 18px;
  padding-bottom: 15px;
  border-bottom: 1px solid #cfd3cc;
}

.section-heading p {
  grid-column: 1 / -1;
  margin: -10px 0 0;
  color: var(--muted);
}

.page-grid {
  display: grid;
  gap: 12px;
}

.page-card {
  overflow: hidden;
  background: rgba(255, 254, 250, 0.82);
  border: 1px solid var(--line);
  border-radius: 14px;
}

.page-card[open] {
  background: var(--card);
  box-shadow: 0 9px 26px rgba(23, 33, 28, 0.07);
}

.page-card summary {
  display: grid;
  grid-template-columns: minmax(180px, 0.75fr) minmax(180px, 1fr) auto;
  gap: 22px;
  align-items: center;
  padding: 18px 20px;
  cursor: pointer;
  list-style: none;
}

.page-card summary::-webkit-details-marker {
  display: none;
}

.page-card summary::after {
  content: "＋";
  color: #748077;
  font-size: 1.25rem;
}

.page-card[open] summary::after {
  content: "−";
}

.title-en {
  font-weight: 800;
}

.title-zh {
  color: var(--muted);
}

.level {
  width: max-content;
  padding: 4px 9px;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 800;
}

.level--core {
  color: var(--green);
  background: var(--green-soft);
}

.level--later {
  color: #7c5119;
  background: var(--gold-soft);
}

.level--advanced {
  color: var(--red);
  background: var(--red-soft);
}

.page-card__body {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(260px, 0.72fr);
  gap: 28px;
  padding: 4px 20px 22px;
  border-top: 1px solid #e7e8e2;
}

.page-card__body h4 {
  margin: 18px 0 7px;
  color: var(--green);
  font-size: 0.79rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.page-card__body p {
  margin: 0;
}

.terms {
  margin: 0;
  padding: 0;
  list-style: none;
}

.terms li {
  display: grid;
  grid-template-columns: minmax(100px, 0.8fr) 1.2fr;
  gap: 12px;
  padding: 7px 0;
  border-bottom: 1px dashed #e0e2dc;
}

.terms b {
  font-size: 0.92rem;
}

.tip,
.warning {
  margin-top: 14px;
  padding: 12px 14px;
  border-radius: 10px;
  font-size: 0.9rem;
}

.tip {
  color: #254737;
  background: var(--green-soft);
}

.warning {
  color: #71332d;
  background: var(--red-soft);
}

.glossary-section {
  margin-top: 80px;
  scroll-margin-top: 24px;
}

.glossary-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.glossary-item {
  padding: 16px 18px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
}

.glossary-item b {
  display: block;
  margin-bottom: 3px;
}

.glossary-item span {
  color: var(--muted);
  font-size: 0.9rem;
}

.checklist {
  margin-top: 64px;
  padding: 32px 34px;
  color: #f6f3e9;
  background: var(--green);
  border-radius: 18px;
}

.checklist ul {
  margin: 22px 0 0;
  padding-left: 22px;
}

.checklist li + li {
  margin-top: 7px;
}

.empty {
  padding: 38px;
  color: var(--muted);
  text-align: center;
  background: var(--card);
  border: 1px dashed var(--line);
  border-radius: 14px;
}

footer {
  padding: 30px 20px 45px;
  color: #6f7973;
  font-size: 0.82rem;
  text-align: center;
}

footer p {
  max-width: 800px;
  margin: 0 auto;
}

@media (max-width: 850px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .sidebar__sticky {
    position: static;
  }

  .section-nav {
    grid-template-columns: repeat(3, 1fr);
  }

  .start-card,
  .page-card__body {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 580px) {
  .hero__inner,
  .layout {
    width: min(100% - 24px, 1180px);
  }

  .hero__inner {
    padding-top: 52px;
  }

  .start-card {
    padding: 24px;
  }

  .start-card ol,
  .glossary-grid,
  .section-nav {
    grid-template-columns: 1fr;
  }

  .page-card summary {
    grid-template-columns: 1fr auto;
    gap: 5px 14px;
  }

  .title-zh,
  .level {
    grid-column: 1;
  }

  .page-card summary::after {
    grid-column: 2;
    grid-row: 1 / 4;
  }

  .terms li {
    grid-template-columns: 1fr;
    gap: 0;
  }
}

@media print {
  body {
    background: #fff;
  }

  .sidebar,
  .search,
  .legend {
    display: none;
  }

  .layout {
    display: block;
    width: 100%;
  }

  .page-card {
    break-inside: avoid;
  }

  .page-card__body {
    display: grid;
  }
}