/* ── Base ── */
  *, *::before, *::after { box-sizing: border-box; }
  html { scroll-behavior: smooth; }
  body { margin: 0; }

  /* ── Scrollbar ── */
  ::-webkit-scrollbar { width: 6px; }
  ::-webkit-scrollbar-track { background: #f1f5f9; }
  ::-webkit-scrollbar-thumb { background: #94a3b8; border-radius: 3px; }
  ::-webkit-scrollbar-thumb:hover { background: #64748b; }

  /* ── Selection ── */
  ::selection { background: #ccfbf1; color: #134e4a; }

  /* ── Nav scroll state ── */
  #nav.scrolled {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(12px);
    box-shadow: 0 1px 0 rgba(0, 0, 0, 0.06);
  }
  #nav.scrolled .text-slate-900 { color: #0f172a; }

  /* ── Mobile menu open ── */
  #mobile-menu.open { opacity: 1; pointer-events: all; }
  #mobile-menu.closed { opacity: 0; pointer-events: none; }

  /* ── Hamburger animation ── */
  #menu-btn.active #bar1 { transform: translateY(4px) rotate(45deg); }
  #menu-btn.active #bar2 { opacity: 0; }
  #menu-btn.active #bar3 { transform: translateY(-4px) rotate(-45deg); width: 6px; }

  /* ── Focus ring global ── */
  :focus-visible { outline: 2px solid #0d9488; outline-offset: 2px; border-radius: 4px; }

  /* ── Reduced motion ── */
  @media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    * { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
  }

  /* ── Scroll reveal (progressive enhancement) ── */
  @media (prefers-reduced-motion: no-preference) {
    .reveal {
      opacity: 0;
      transform: translateY(24px);
      transition: opacity 0.7s cubic-bezier(0.22, 1, 0.36, 1), transform 0.7s cubic-bezier(0.22, 1, 0.36, 1);
    }
    .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; }
  }