/* ============================================================
   页脚 · is-footer（v3 · 最深蓝）
   ============================================================ */

is-footer { display: block; }

.footer {
  background: var(--color-ink-deep);
  color: var(--color-text-muted);
  padding-top: clamp(3rem, 6vw, 5rem);
  border-top: 1px solid var(--color-line-soft);
}

.footer__main {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: clamp(2rem, 4vw, 4rem);
  padding-bottom: clamp(2.25rem, 4vw, 3rem);
  border-bottom: 1px solid var(--color-line-soft);
}

.footer__brand-name { display: flex; align-items: center; gap: 0.75rem; color: var(--color-heading); font-size: 1.0625rem; font-weight: 700; letter-spacing: 0.04em; }
.footer__brand-mark { width: 36px; height: 36px; flex: none; object-fit: contain; border-radius: 6px; }
.footer__brand-tagline { margin-top: 0.875rem; font-size: 0.875rem; color: var(--color-text-faint); max-width: 300px; line-height: 1.9; }

.footer__col-title { font-size: 0.6875rem; font-weight: 600; letter-spacing: 0.18em; text-transform: uppercase; color: var(--color-accent); margin-bottom: 1.125rem; }
.footer__col-list { display: flex; flex-direction: column; gap: 0.75rem; }
.footer__col-link { font-size: 0.875rem; color: var(--color-text-muted); transition: color var(--dur) var(--ease); }
.footer__col-link:hover { color: var(--color-heading); }

.footer__bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  padding-block: 1.5rem;
  font-size: 0.75rem;
  color: var(--color-text-faint);
}

@media (max-width: 1024px) { .footer__main { grid-template-columns: 1fr 1fr; } }
@media (max-width: 640px)  { .footer__main { grid-template-columns: 1fr; } }