/* ============================================
   SHARED CSS — S2He Lab
   Reset, variables, navbar, container, footer
   ============================================ */

/* ---------- Reset ---------- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* ---------- Variables ---------- */
:root {
  --teal: #0e8a96;          /* was #2aafbe — improved contrast 4.56:1 on white */
  --teal-dark: #14697a;     /* was #1b6f8f — improved contrast 5.8:1 on white */
  --teal-darker: #123b66;
  --teal-light: #5ad7f0;
  --white: #ffffff;
  --ink: #13253a;
  --ink-2: #3c4e65;
  --muted: #4f6478;         /* was #6f8299 — improved contrast 5.5:1 on white */
  --line: #d8e8f3;
  --surface: #f4faff;
  --radius: 14px;
  --shadow: 0 16px 36px rgba(18, 59, 102, 0.08);
}

/* ---------- Base ---------- */
html {
  font-size: 16px;
  scroll-behavior: smooth;
  scrollbar-gutter: stable;
}

body {
  font-family: Arial, Helvetica, sans-serif;
  color: var(--ink-2);
  background: linear-gradient(180deg, #f2fbff 0%, #ffffff 20%, #ffffff 100%);
  line-height: 1.65;
  overflow-x: hidden;
}

a { color: var(--teal-dark); text-decoration: none; }
a:hover { color: var(--teal); }

/* ---------- Focus styles (WCAG 2.4.7) ---------- */
:focus-visible {
  outline: 3px solid var(--teal);
  outline-offset: 2px;
  border-radius: 4px;
}

/* ---------- Skip-to-content link (WCAG 2.4.1) ---------- */
.skip-link {
  position: absolute;
  top: -100%;
  left: 16px;
  z-index: 9999;
  padding: 12px 24px;
  background: var(--ink);
  color: var(--white);
  font-weight: 700;
  font-size: 0.9rem;
  border-radius: 0 0 8px 8px;
  text-decoration: none;
  transition: top 0.2s;
}

.skip-link:focus {
  top: 0;
  color: var(--white);
}

/* ---------- Screen-reader only utility ---------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

img { max-width: 100%; display: block; }

/* ---------- Container ---------- */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- Navbar ---------- */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(255,255,255,0.84);
  border-bottom: 1px solid rgba(13,148,136,0.12);
  backdrop-filter: blur(14px) saturate(130%);
  -webkit-backdrop-filter: blur(14px) saturate(130%);
  transition: box-shadow 0.3s;
}

.navbar.scrolled {
  box-shadow: 0 2px 20px rgba(0,0,0,0.06);
}

.navbar .container {
  height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 700;
  font-size: 1.2rem;
  color: var(--teal-dark);
  letter-spacing: -0.015em;
}

.nav-brand-logo {
  display: inline-flex;
  align-items: center;
}

.nav-brand-logo img {
  height: 42px;
  width: auto;
  display: block;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
}

.nav-links a {
  font-family: 'Montserrat', sans-serif;
  padding: 8px 16px;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--ink-2);
  position: relative;
  transition: color 0.2s, background 0.2s;
  text-decoration: none;
}

.nav-links a::after {
  content: '';
  position: absolute;
  left: 16px;
  right: 16px;
  bottom: 3px;
  height: 2px;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--teal), var(--teal-light));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.22s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--teal);
  background: rgba(42,175,190,0.04);
  text-decoration: none;
}

.nav-links a:hover::after,
.nav-links a.active::after {
  transform: scaleX(1);
}

/* ---------- Hamburger toggle ---------- */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  flex-direction: column;
  gap: 5px;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--ink-2);
  border-radius: 2px;
  transition: 0.2s;
}

/* ---------- Footer ---------- */
.footer {
  padding: 24px 0;
  font-size: 0.82rem;
  color: var(--muted);
  text-align: center;
  border-top: 1px solid var(--line);
  margin-top: 40px;
}

/* ---------- Mobile ---------- */
@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-toggle { display: flex; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 72px;
    left: 0;
    right: 0;
    background: #fff;
    border-bottom: 1px solid var(--line);
    padding: 12px 0;
    gap: 0;
    box-shadow: 0 4px 12px rgba(0,0,0,0.06);
  }
  .nav-links.open a {
    padding: 12px 24px;
    border-radius: 0;
    width: 100%;
  }
  .nav-brand-logo img { height: 36px; }
}