/* ── Base ───────────────────────────────────────────────── */
  *, *::before, *::after { box-sizing: border-box; }
  html { scroll-behavior: smooth; scroll-padding-top: 80px; }
  body { margin: 0; -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; }

  /* ── Selection ────────────────────────────────────────────── */
  ::selection { background: #0d9488; color: #fff; }

  /* ── Scrollbar ────────────────────────────────────────────── */
  ::-webkit-scrollbar { width: 6px; }
  ::-webkit-scrollbar-track { background: #fafaf9; }
  ::-webkit-scrollbar-thumb { background: #94a3b8; border-radius: 3px; }
  ::-webkit-scrollbar-thumb:hover { background: #64748b; }

  /* ── Header transition ───────────────────────────────────── */
  #site-header { background: transparent; }
  #site-header.scrolled {
    background: rgba(250, 250, 249, 0.92);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    box-shadow: 0 1px 0 rgba(0,0,0,0.06);
  }

  /* ── Nav links underline ─────────────────────────────────── */
  .nav-link { position: relative; }
  .nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 1px;
    background: #0d9488;
    transition: width 0.3s ease;
  }
  .nav-link:hover::after { width: 100%; }

  /* ── Mobile menu ─────────────────────────────────────────── */
  #mobile-menu.open { opacity: 1 !important; pointer-events: all !important; }
  .menu-line.active:nth-child(1) { transform: translateY(6px) rotate(45deg); }
  .menu-line.active:nth-child(2) { opacity: 0; }
  .menu-line.active:nth-child(3) { transform: translateY(-6px) rotate(-45deg); width: 5px; }

  /* ── Scroll reveal (progressive enhancement) ─────────────── */
  @media (prefers-reduced-motion: no-preference) {
    .reveal {
      opacity: 0;
      transform: translateY(24px);
      transition: opacity 0.7s ease, transform 0.7s ease;
    }
    .reveal.revealed {
      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; }
  }
  @media (prefers-reduced-motion: reduce) {
    .reveal { opacity: 1; transform: none; transition: none; }
  }

  /* ── Smooth image loading ────────────────────────────────── */
  img { display: block; max-width: 100%; }