:root {
  color-scheme: light;
  --brand: #0c7489;
  --brand-dark: #095466;
  --text: #1b1f24;
  --muted: #5f6b7a;
  --border: #d8e6e8;
  font-family: "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: #f5fafb;
}
* { box-sizing: border-box; }
body { margin: 0; line-height: 1.75; }
a { color: var(--brand); text-underline-offset: 0.2em; }
a:hover, a:focus { color: var(--brand-dark); }
header, main, footer { width: min(100% - 2rem, 52rem); margin-inline: auto; }
header { padding: 2rem 0 1.25rem; }
.brand { font-weight: 800; text-decoration: none; }
main {
  padding: clamp(1.5rem, 5vw, 3rem);
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 1rem;
  box-shadow: 0 1.5rem 4rem -3.25rem var(--brand);
}
h1 { margin-top: 0; line-height: 1.25; font-size: clamp(2rem, 7vw, 3rem); }
h2 { margin-top: 2rem; line-height: 1.35; }
.summary { color: var(--muted); font-size: 1.08rem; }
.meta { color: var(--muted); font-size: 0.9rem; }
.answer, .callout {
  margin: 1.5rem 0;
  padding: 1rem 1.2rem;
  background: #edf7f8;
  border-left: 0.3rem solid var(--brand);
  border-radius: 0.5rem;
}
.content-nav { display: flex; flex-wrap: wrap; gap: 0.55rem 1rem; margin: 1.5rem 0; }
.formula { padding: 1rem; overflow-x: auto; background: #f3f5f6; border-radius: 0.6rem; font-weight: 700; }
table { width: 100%; border-collapse: collapse; margin: 1.25rem 0; }
th, td { padding: 0.7rem; border: 1px solid var(--border); text-align: left; vertical-align: top; }
th { background: #edf7f8; }
@media (max-width: 640px) {
  table { display: block; overflow-x: auto; }
}
footer { padding: 1.5rem 0 3rem; color: var(--muted); font-size: 0.9rem; }
.footer-links { display: flex; flex-wrap: wrap; gap: 0.6rem 1rem; margin-bottom: 0.5rem; }
code { overflow-wrap: anywhere; }
a:focus-visible { outline: 3px solid #f2c14e; outline-offset: 3px; }