/* 布局：容器 / 头部 / 分区 / 揭示动画 / 页脚 */
.container {
  width: 100%;
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: clamp(20px, 5vw, 40px);
}

main { position: relative; z-index: 2; }

.section {
  padding-block: clamp(72px, 11vw, var(--space-6));
  position: relative;
}
.section + .section { border-top: 1px solid var(--line); }

.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: var(--space-3);
  margin-bottom: clamp(32px, 5vw, 56px);
}
.section-title {
  font-size: clamp(1.9rem, 4.4vw, 3rem);
  margin-top: 14px;
}
.section-head .lede { max-width: 44ch; font-size: 0.98rem; }

/* ---------- 头部导航 ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  height: var(--header-h);
  display: flex;
  align-items: center;
  transition: background-color var(--t-base) var(--ease-out),
    backdrop-filter var(--t-base) var(--ease-out),
    border-color var(--t-base) var(--ease-out);
  border-bottom: 1px solid transparent;
}
.site-header.is-stuck {
  background: rgba(7, 9, 13, 0.72);
  backdrop-filter: blur(14px) saturate(150%);
  border-bottom-color: var(--line);
}
.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  width: 100%;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.brand__mark {
  width: 30px;
  height: 30px;
  border-radius: 9px;
  display: grid;
  place-items: center;
  font-size: 0.85rem;
  color: #04141a;
  background: var(--grad-accent);
  box-shadow: 0 8px 22px -12px rgba(110, 231, 255, 0.9);
  transition: transform var(--t-base) var(--ease-spring);
}
.brand:hover .brand__mark { transform: rotate(-8deg) scale(1.08); }

.nav__links {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
  margin: 0;
  padding: 0;
}
.nav__link {
  position: relative;
  padding: 8px 14px;
  border-radius: 999px;
  font-size: 0.9rem;
  color: var(--text-dim);
  transition: color var(--t-base) var(--ease-out), background-color var(--t-base) var(--ease-out);
}
.nav__link::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 2px;
  width: 0;
  height: 2px;
  border-radius: 2px;
  background: var(--accent);
  transform: translateX(-50%);
  transition: width var(--t-base) var(--ease-out);
}
.nav__link:hover { color: var(--text); background: var(--bg-card); }
.nav__link:hover::after,
.nav__link.is-active::after { width: 18px; }
.nav__link.is-active { color: var(--accent); }

.nav__toggle { display: none; }

@media (max-width: 820px) {
  .nav__links {
    position: fixed;
    inset: var(--header-h) 0 auto 0;
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
    padding: 14px clamp(20px, 5vw, 40px) 26px;
    background: rgba(7, 9, 13, 0.96);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--line);
    transform: translateY(-12px);
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--t-base) var(--ease-out), transform var(--t-base) var(--ease-out);
  }
  .nav__links.is-open { opacity: 1; transform: none; pointer-events: auto; }
  .nav__link { padding: 12px 4px; border-radius: 8px; }
  .nav__toggle {
    display: grid;
    gap: 5px;
    padding: 10px;
    border-radius: 10px;
    border: 1px solid var(--line);
  }
  .nav__toggle span {
    width: 18px;
    height: 2px;
    background: var(--text);
    transition: transform var(--t-base) var(--ease-out), opacity var(--t-fast);
  }
  .nav__toggle.is-open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
  .nav__toggle.is-open span:nth-child(2) { opacity: 0; }
  .nav__toggle.is-open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }
}

/* ---------- 揭示动画 ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(26px);
  transition: opacity var(--t-slow) var(--ease-out), transform var(--t-slow) var(--ease-out);
  transition-delay: var(--reveal-delay, 0ms);
}
[data-reveal].is-visible { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  [data-reveal] { opacity: 1; transform: none; }
}

/* ---------- 页脚 ---------- */
.site-footer {
  position: relative;
  z-index: 2;
  border-top: 1px solid var(--line);
  padding-block: 40px;
  color: var(--text-mute);
  font-size: 0.88rem;
}
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  align-items: center;
  justify-content: space-between;
}
.footer-links { display: flex; gap: 18px; }
.footer-links a { transition: color var(--t-base) var(--ease-out); }
.footer-links a:hover { color: var(--accent); }