/* 关于页：介绍本网站。复用全站配色与卡片语言。 */

.about { width: min(960px, 100%); margin: 0 auto; padding: 20px 16px 8px; }
.about-hero {
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: 20px;
  padding: 30px 26px 26px;
  box-shadow: var(--shadow);
}
.about-hero h1 {
  margin: 0 0 10px;
  font-size: clamp(1.7rem, 4vw, 2.45rem);
  line-height: 1.18;
  letter-spacing: -0.03em;
  font-weight: 750;
}
.about-hero .lede { margin: 0; font-size: 1.06rem; color: var(--muted); max-width: 42em; }
.about-hero .hero-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 18px; }
.about-hero .btn { flex: 0 1 auto; }

.about-section { margin: 32px 0 0; }
.about-section h2 {
  margin: 0 0 12px;
  font-size: 1.2rem;
  letter-spacing: -0.02em;
}
.about-section > p { margin: 0 0 12px; color: var(--muted); max-width: 44em; }
.about-list { margin: 0; padding-left: 1.25em; color: var(--muted); max-width: 44em; }
.about-list li { margin: 7px 0; }
.about-list strong { color: var(--text); }

.about-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 12px;
}
.about-card {
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px 16px 18px;
  border-top: 3px solid var(--brand);
  min-width: 0;
}
.about-card.is-chinese { border-top-color: #9f1239; }
.about-card.is-english { border-top-color: #4338ca; }
.about-card.is-physics { border-top-color: #b45309; }
.about-card h3 { margin: 0 0 6px; font-size: 1.04rem; letter-spacing: -0.02em; }
.about-card p { margin: 0; font-size: 0.92rem; color: var(--muted); }

.about-steps {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}
.about-steps li {
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px 16px 18px;
  min-width: 0;
}
.about-steps .step-no {
  display: inline-flex;
  width: 28px; height: 28px;
  border-radius: 50%;
  align-items: center; justify-content: center;
  background: var(--brand-soft);
  color: var(--brand-strong);
  font-weight: 750; font-size: 0.92rem;
}
.about-steps h3 { margin: 10px 0 4px; font-size: 1.02rem; letter-spacing: -0.02em; }
.about-steps p { margin: 0; color: var(--muted); font-size: 0.93rem; }

.about-callout {
  background: var(--brand-soft);
  border: 1px solid color-mix(in srgb, var(--brand) 30%, transparent);
  border-radius: var(--radius);
  padding: 16px 18px;
  color: var(--text);
}
.about-callout p { margin: 0 0 10px; line-height: 1.6; }
.about-callout p:last-child { margin-bottom: 0; }
.about-callout strong { color: var(--brand-strong); }
.about-callout a { color: var(--brand-strong); font-weight: 700; }

.about-cta { display: flex; flex-wrap: wrap; gap: 10px; margin: 16px 0 0; }
.about-cta .btn { flex: 0 1 auto; }

@media (max-width: 800px) {
  .about-steps { grid-template-columns: 1fr; }
  .about-grid { grid-template-columns: 1fr 1fr; }
  .about-hero { padding: 24px 18px 20px; }
}
@media (max-width: 520px) {
  .about-grid { grid-template-columns: 1fr; }
  .about-section { margin-top: 26px; }
}