:root {
  --green: #198754;
  --green-soft: #d1e7dd;
  --ink: #3d3d3d;
  --muted: #6c757d;
  --line: #e9ecef;
  --bg: #f7f8f6;
  --card: #ffffff;
  --danger: #c0392b;
  --measure: 42rem;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  min-height: 100%;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  font-family: ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.7;
}

a { color: var(--green); text-decoration: none; }
a:hover { text-decoration: underline; }

.site-header, .site-footer {
  flex-shrink: 0;
  background: #fff;
  border-bottom: 1px solid var(--line);
}

.site-footer {
  border-top: 1px solid var(--line);
  border-bottom: 0;
}

.site-header-inner,
.site-footer-inner,
.page {
  width: min(var(--measure), calc(100% - 2rem));
  margin: 0 auto;
}

.site-header-inner,
.site-footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: 3.5rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--green);
  font-weight: 700;
  text-decoration: none;
}

.brand:hover { text-decoration: none; }
.brand img { width: 28px; height: 28px; display: block; }

.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem 1.15rem;
  font-size: 0.95rem;
}
.site-nav a {
  color: var(--ink);
  text-decoration: none;
}
.site-nav a:hover,
.site-nav a:focus-visible {
  color: var(--green);
}

.page {
  flex: 1 0 auto;
  padding: 1.5rem 0 3rem;
}

.breadcrumb {
  font-size: 0.9rem;
  color: var(--muted);
  margin-bottom: 1rem;
}

.breadcrumb a { color: var(--muted); }

.answer-box {
  background: var(--green-soft);
  border: 1px solid #badbcc;
  border-radius: 12px;
  padding: 1rem 1.15rem;
  margin: 0 0 1.25rem;
}

.answer-box .kicker {
  margin: 0 0 0.25rem;
  color: var(--green);
  font-size: 0.85rem;
  font-weight: 700;
}

.answer-box p { margin: 0; font-size: 1.25rem; }

h1 {
  font-size: clamp(1.6rem, 3vw, 2rem);
  line-height: 1.3;
  margin: 0 0 0.75rem;
}

.lede, .summary { color: #4b4b4b; }

.hub-hero { margin: 0 0 1.75rem; }
.hub-hero h1 { margin-bottom: 0.4rem; }
.hub-hero .lede {
  margin: 0;
  font-size: 1rem;
  color: var(--muted);
}

.meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 0.75rem 0 1.25rem;
  color: var(--muted);
  font-size: 0.9rem;
}

.badge {
  display: inline-block;
  background: #eef6f1;
  color: var(--green);
  border-radius: 999px;
  padding: 0.15rem 0.6rem;
  font-size: 0.8rem;
}

.section { margin: 2rem 0; }
.section h2 {
  font-size: 1.25rem;
  margin: 0 0 0.75rem;
}

.note-list, .faq-list { padding-left: 1.15rem; }
.note-list li, .faq-list li { margin: 0.4rem 0; }

.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.chip {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 0.25rem 0.7rem;
  font-size: 0.95rem;
}

.example-card, .related-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 0.9rem 1rem;
  margin: 0.7rem 0;
}

.example-en {
  font-size: 1.05rem;
  font-weight: 600;
}

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

.pair-table {
  width: 100%;
  border-collapse: collapse;
  background: #fff;
  border-radius: 12px;
  overflow: hidden;
}

#mistakes { overflow-x: auto; }
.pair-table th, .pair-table td {
  border-bottom: 1px solid var(--line);
  text-align: left;
  padding: 0.7rem 0.8rem;
  vertical-align: top;
}

.pair-table th { background: #f3f6f4; font-size: 0.85rem; }
.pair-table + .pair-table { margin-top: 1.25rem; }
.pair-table del {
  color: var(--danger);
  text-decoration: line-through;
  text-decoration-thickness: 2px;
}
.pair-table del.keep-hyphen {
  text-decoration: none;
}
.pair-table ins {
  color: var(--green);
  font-weight: 600;
  text-decoration: none;
}
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.related-grid {
  display: grid;
  gap: 0.75rem;
}

.cta-panel {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  background: #fff;
  border: 1px solid var(--green-soft);
  border-radius: 14px;
  padding: 1.1rem 1.2rem;
  margin: 2rem 0;
}

.cta-panel p { margin: 0.25rem 0 0; color: var(--muted); }

.btn {
  display: inline-block;
  background: var(--green);
  color: #fff !important;
  text-decoration: none !important;
  border-radius: 999px;
  padding: 0.6rem 1rem;
  font-weight: 700;
  white-space: nowrap;
}

.article-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--line);
}

.article-card {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  padding: 1rem 0;
  border-bottom: 1px solid var(--line);
  color: inherit;
  text-decoration: none;
}

.article-card:hover,
.article-card:focus-visible {
  text-decoration: none;
}

.article-card:hover strong,
.article-card:focus-visible strong {
  color: var(--green);
}

.article-card strong {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--ink);
}

.article-card .en {
  color: var(--muted);
  font-size: 0.95rem;
}

.empty { color: var(--muted); }

@media (max-width: 720px) {
  .cta-panel, .site-header-inner, .site-footer-inner {
    flex-direction: column;
    align-items: flex-start;
  }
}