:root {
  color-scheme: light;
  --brand: #153bc0;
  --brand-dark: #102b86;
  --ink: #18202d;
  --muted: #647084;
  --line: #dfe4eb;
  --surface: #f5f7fa;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: white;
  font-family: Poppins, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  line-height: 1.75;
}
a { color: var(--brand-dark); text-underline-offset: 3px; }
a:focus-visible { outline: 3px solid #87a1ff; outline-offset: 3px; }
img { max-width: 100%; height: auto; }

.knowledge-header {
  min-height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 16px max(24px, calc((100vw - 1120px) / 2));
  border-bottom: 1px solid var(--line);
}
.knowledge-brand { color: var(--ink); font-weight: 720; text-decoration: none; }
.knowledge-header span { color: var(--muted); font-size: 0.86rem; }
.knowledge-nav {
  display: flex;
  gap: 4px;
  padding: 10px max(20px, calc((100vw - 1120px) / 2));
  overflow-x: auto;
  background: var(--surface);
  border-bottom: 1px solid var(--line);
  white-space: nowrap;
}
.knowledge-nav a { padding: 8px 12px; color: #465166; border-radius: 6px; font-size: 0.86rem; text-decoration: none; }
.knowledge-nav a:hover, .knowledge-nav a[aria-current="page"] { color: var(--brand-dark); background: white; }

.knowledge-main { width: min(100% - 40px, 1120px); margin: 0 auto; padding: clamp(54px, 8vw, 100px) 0; }
.knowledge-intro { max-width: 800px; }
.knowledge-intro--compact { padding-bottom: 32px; border-bottom: 1px solid var(--line); }
.knowledge-eyebrow { margin: 0 0 12px; color: var(--brand); font-size: 0.78rem; font-weight: 750; letter-spacing: 0.08em; text-transform: uppercase; }
.knowledge-intro h1 { margin: 0; font-size: clamp(2.2rem, 6vw, 4.6rem); line-height: 1.12; letter-spacing: -0.045em; }
.knowledge-intro > p:not(.knowledge-eyebrow, .knowledge-updated) { max-width: 66ch; margin: 22px 0 0; color: #465166; font-size: clamp(1rem, 2vw, 1.15rem); }
.knowledge-updated { margin: 16px 0 0; color: var(--muted); font-size: 0.78rem; }

.knowledge-sections { margin-top: clamp(48px, 8vw, 88px); border-top: 1px solid var(--line); }
.knowledge-section { display: grid; grid-template-columns: minmax(210px, 0.8fr) minmax(0, 1.5fr); gap: 40px; padding: 36px 0; border-bottom: 1px solid var(--line); }
.knowledge-section h2 { margin: 0; font-size: 1.45rem; }
.knowledge-section h2 a { color: inherit; }
.knowledge-section ul { margin: 0; padding-left: 1.25rem; color: #465166; }

.knowledge-entries { margin-top: 12px; }
.knowledge-entry { display: grid; grid-template-columns: 56px minmax(0, 1fr); gap: 24px; padding: clamp(34px, 6vw, 64px) 0; border-bottom: 1px solid var(--line); }
.knowledge-entry__index { color: var(--brand); font-size: 0.76rem; font-weight: 750; letter-spacing: 0.08em; }
.knowledge-entry__content { max-width: 820px; }
.knowledge-entry h2 { margin: 0; font-size: clamp(1.35rem, 3vw, 2rem); line-height: 1.3; }
.knowledge-summary { margin: 12px 0 0; color: #465166; font-size: 1.04rem; font-weight: 580; }
.knowledge-entry img { max-height: 480px; margin-top: 26px; border: 1px solid var(--line); object-fit: contain; }
.knowledge-copy { margin-top: 24px; color: #303b4d; }
.knowledge-copy p { margin: 0; white-space: normal; }
.knowledge-copy p + p { margin-top: 1em; }
.knowledge-source { margin: 20px 0 0; font-size: 0.86rem; }
.knowledge-empty { padding: 56px 0; color: var(--muted); }

.knowledge-footer { padding: 34px max(20px, calc((100vw - 1120px) / 2)); color: var(--muted); background: var(--surface); border-top: 1px solid var(--line); font-size: 0.82rem; }
.knowledge-footer p { margin: 0; }
.knowledge-footer p + p { margin-top: 6px; }

@media (max-width: 700px) {
  .knowledge-header { align-items: flex-start; flex-direction: column; gap: 4px; }
  .knowledge-main { width: min(100% - 32px, 1120px); }
  .knowledge-section { grid-template-columns: 1fr; gap: 14px; }
  .knowledge-entry { grid-template-columns: 1fr; gap: 10px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}