/* ============================================================
   布局：容器 / 栅格 / 区块 / 导航 / 页脚
   ============================================================ */

/* ---------- 容器 ---------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--s-5);
}

.container-narrow {
  width: 100%;
  max-width: var(--container-narrow);
  margin-inline: auto;
  padding-inline: var(--s-5);
}

/* ---------- 区块 ---------- */
.section {
  position: relative;
  padding-block: var(--s-10);
}

.section--tight {
  padding-block: var(--s-9);
}

.section-head {
  max-width: 720px;
  margin-bottom: var(--s-8);
}

.section-head--center {
  margin-inline: auto;
  text-align: center;
}

.section-label {
  display: inline-flex;
  align-items: center;
  gap: var(--s-2);
  margin-bottom: var(--s-4);
  padding: 6px 14px;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--brand-3);
  background: rgba(34, 211, 238, 0.08);
  border: 1px solid rgba(34, 211, 238, 0.2);
  border-radius: 100px;
}

.section-label::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--brand-3);
  box-shadow: 0 0 8px var(--brand-3);
}

.section-desc {
  margin-top: var(--s-4);
  font-size: 1.05rem;
  color: var(--text-3);
}

/* ---------- 栅格 ---------- */
.grid {
  display: grid;
  gap: var(--s-5);
}

.grid-2 {
  grid-template-columns: repeat(2, 1fr);
}

.grid-3 {
  grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
  grid-template-columns: repeat(4, 1fr);
}

/* ---------- 顶部导航 ---------- */
.nav {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 100;
  height: 68px;
  display: flex;
  align-items: center;
  transition: background 0.35s var(--ease-out),
    border-color 0.35s var(--ease-out), backdrop-filter 0.35s var(--ease-out);
  border-bottom: 1px solid transparent;
}

.nav--scrolled {
  background: rgba(6, 8, 16, 0.78);
  border-bottom-color: var(--line-1);
  backdrop-filter: blur(18px) saturate(1.4);
  -webkit-backdrop-filter: blur(18px) saturate(1.4);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--s-5);
}

.nav__brand {
  display: flex;
  align-items: center;
  gap: var(--s-3);
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--text-1);
  letter-spacing: -0.01em;
}

.nav__logo {
  width: 30px;
  height: 30px;
  border-radius: 8px;
  background: var(--grad-brand);
  display: grid;
  place-items: center;
  font-size: 0.85rem;
  font-weight: 800;
  color: #fff;
  box-shadow: 0 4px 14px rgba(59, 130, 246, 0.4);
}

.nav__links {
  display: flex;
  align-items: center;
  gap: var(--s-6);
  list-style: none;
}

.nav__links a {
  position: relative;
  font-size: 0.92rem;
  color: var(--text-3);
  transition: color 0.25s var(--ease-out);
}

.nav__links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -6px;
  width: 0;
  height: 2px;
  background: var(--grad-brand);
  border-radius: 2px;
  transition: width 0.3s var(--ease-out);
}

.nav__links a:hover {
  color: var(--text-1);
}

.nav__links a:hover::after {
  width: 100%;
}

.nav__actions {
  display: flex;
  align-items: center;
  gap: var(--s-3);
}

.nav__toggle {
  display: none;
  width: 40px;
  height: 40px;
  border-radius: var(--r-sm);
  border: 1px solid var(--line-2);
  place-items: center;
}

.nav__toggle span {
  display: block;
  width: 16px;
  height: 1.5px;
  background: var(--text-2);
  position: relative;
  transition: transform 0.3s var(--ease-out);
}

.nav__toggle span::before,
.nav__toggle span::after {
  content: "";
  position: absolute;
  left: 0;
  width: 16px;
  height: 1.5px;
  background: var(--text-2);
  transition: transform 0.3s var(--ease-out), opacity 0.2s;
}

.nav__toggle span::before {
  top: -5px;
}

.nav__toggle span::after {
  top: 5px;
}

.nav__toggle[aria-expanded="true"] span {
  background: transparent;
}

.nav__toggle[aria-expanded="true"] span::before {
  transform: translateY(5px) rotate(45deg);
}

.nav__toggle[aria-expanded="true"] span::after {
  transform: translateY(-5px) rotate(-45deg);
}

/* ---------- 页脚 ---------- */
.footer {
  position: relative;
  padding-block: var(--s-9) var(--s-6);
  border-top: 1px solid var(--line-1);
  background: var(--bg-1);
}

.footer__grid {
  display: grid;
  grid-template-columns: 1.6fr repeat(3, 1fr);
  gap: var(--s-7);
  margin-bottom: var(--s-8);
}

.footer__brand p {
  margin-top: var(--s-4);
  max-width: 320px;
  font-size: 0.9rem;
  color: var(--text-4);
  line-height: 1.8;
}

.footer__col h4 {
  margin-bottom: var(--s-4);
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--text-3);
}

.footer__col ul {
  list-style: none;
  display: grid;
  gap: var(--s-3);
}

.footer__col a {
  font-size: 0.9rem;
  color: var(--text-4);
  transition: color 0.25s var(--ease-out);
}

.footer__col a:hover {
  color: var(--brand-3);
}

.footer__bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--s-4);
  padding-top: var(--s-5);
  border-top: 1px solid var(--line-1);
  font-size: 0.82rem;
  color: var(--text-4);
}

/* ---------- 响应式断点 ---------- */
@media (max-width: 1024px) {
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }

  .footer__grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  :root {
    --s-9: 64px;
    --s-10: 80px;
  }

  .nav__links {
    position: fixed;
    inset: 68px 0 auto 0;
    flex-direction: column;
    gap: 0;
    padding: var(--s-4) var(--s-5) var(--s-6);
    background: rgba(6, 8, 16, 0.97);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--line-2);
    transform: translateY(-12px);
    opacity: 0;
    pointer-events: none;
    transition: transform 0.3s var(--ease-out), opacity 0.3s var(--ease-out);
  }

  .nav__links[data-open="true"] {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .nav__links li {
    width: 100%;
    border-bottom: 1px solid var(--line-1);
  }

  .nav__links a {
    display: block;
    padding: var(--s-4) 0;
    font-size: 1rem;
  }

  .nav__links a::after {
    display: none;
  }

  .nav__toggle {
    display: grid;
  }

  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }

  .footer__grid {
    grid-template-columns: 1fr;
    gap: var(--s-6);
  }

  .footer__bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}