/* ── Base ── */
  *, *::before, *::after { box-sizing: border-box; }
  html { scroll-behavior: smooth; scroll-padding-top: 80px; }
  body { margin: 0; }
  img { display: block; max-width: 100%; }

  /* ── Mobile menu transitions ── */
  #mobile-menu {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease, padding 0.35s ease;
  }
  #mobile-menu.open {
    max-height: 400px;
    padding-top: 0.5rem;
    padding-bottom: 0.5rem;
  }
  .mobile-link {
    display: block;
    padding: 0.5rem 0;
    border-bottom: 1px solid #f1f5f9;
    transition: color 0.2s;
  }
  .mobile-link:hover { color: #0d9488; }
  .mobile-link:last-child { border-bottom: none; }

  /* ── Nav shadow on scroll ── */
  #nav.scrolled {
    box-shadow: 0 1px 20px rgba(0,0,0,0.08);
  }

  /* ── Scroll reveal (below-fold only, progressive enhancement) ── */
  @media (prefers-reduced-motion: no-preference) {
    .reveal {
      opacity: 0;
      transform: translateY(24px);
      transition: opacity 0.7s ease, transform 0.7s ease;
    }
    .reveal.visible {
      opacity: 1;
      transform: translateY(0);
    }
    .reveal-delay-1 { transition-delay: 0.1s; }
    .reveal-delay-2 { transition-delay: 0.2s; }
    .reveal-delay-3 { transition-delay: 0.3s; }
  }

  /* ── Fallback: content always visible if JS disabled or prefers-reduced-motion ── */
  @media (prefers-reduced-motion: reduce) {
    .reveal { opacity: 1; transform: none; }
  }
  @supports not (animation-timeline: view()) {
    .reveal { opacity: 1; transform: none; }
  }