/* === LONGEVITY TECHNOLOGY – Minimalist Black/White === */
:root {
  --bg: #0a0a0a;
  --bg-alt: #111;
  --bg-card: #161616;
  --text: #e0e0e0;
  --text-dim: #999;
  --accent: #fff;
  --border: #2a2a2a;
  --max-w: 960px;
  --ff: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body { font-family: var(--ff); background: var(--bg); color: var(--text); line-height: 1.7; }

/* Links */
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* Container */
.container { max-width: var(--max-w); margin: 0 auto; padding: 0 1.5rem; }

/* Header */
header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(10,10,10,.92); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  padding: .75rem 0;
}
header .container { display: flex; align-items: center; justify-content: space-between; gap: 1rem; }
header img { height: 36px; width: auto; }
nav { display: flex; gap: .25rem; flex-wrap: wrap; }
nav a {
  font-size: .8rem; padding: .35rem .65rem; border-radius: 4px;
  color: var(--text-dim); transition: color .2s;
}
nav a:hover { color: var(--accent); text-decoration: none; }

/* Hero */
.hero {
  padding: 4rem 0 3rem;
  border-bottom: 1px solid var(--border);
}
.hero h1 { font-size: 2rem; font-weight: 700; letter-spacing: -.02em; margin-bottom: .75rem; color: #fff; }
.hero .lead { font-size: 1.1rem; color: var(--text-dim); max-width: 640px; }

/* Sections */
section { padding: 3rem 0; border-bottom: 1px solid var(--border); }
section:last-of-type { border-bottom: none; }

h2 { font-size: 1.5rem; font-weight: 700; margin-bottom: 1.5rem; color: #fff; letter-spacing: -.01em; }
h3 { font-size: 1.15rem; font-weight: 600; margin: 2rem 0 .75rem; color: #fff; }
h4 { font-size: 1rem; font-weight: 600; margin: 1.5rem 0 .5rem; color: #ddd; }
h5 { font-size: .9rem; font-weight: 600; margin: 1rem 0 .4rem; color: #ccc; text-transform: uppercase; letter-spacing: .04em; }

p { margin-bottom: .75rem; }
ul, ol { margin: .5rem 0 1rem 1.5rem; }
li { margin-bottom: .35rem; }

/* Cards / Content blocks */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}
.card h3 { margin-top: 0; }

/* Tables */
table { width: 100%; border-collapse: collapse; margin: 1rem 0 1.5rem; font-size: .9rem; }
thead { background: var(--bg-card); }
th, td { padding: .6rem .75rem; border: 1px solid var(--border); text-align: left; vertical-align: top; }
th { font-weight: 600; color: #fff; white-space: nowrap; }
td { color: var(--text); }

/* Badge */
.badge {
  display: inline-block; font-size: .75rem; padding: .2rem .5rem;
  border: 1px solid var(--border); border-radius: 3px; color: var(--text-dim);
  margin-right: .4rem; margin-bottom: .3rem;
}

/* Section nav / TOC */
.toc { margin: 1rem 0 2rem; }
.toc a { display: inline-block; margin: .15rem .4rem .15rem 0; font-size: .85rem; color: var(--text-dim); }
.toc a:hover { color: #fff; }

/* Sub-section divider */
.divider { border-top: 1px solid var(--border); margin: 2.5rem 0; }

/* References */
.ref-list { font-size: .8rem; line-height: 1.6; color: var(--text-dim); }
.ref-list li { margin-bottom: .4rem; word-break: break-word; }
.ref-list a { color: var(--text-dim); }
.ref-list a:hover { color: #fff; }

/* Footer */
footer {
  padding: 2rem 0;
  border-top: 1px solid var(--border);
  font-size: .8rem; color: var(--text-dim);
  text-align: center;
}

/* Hamburger toggle (CSS-only) */
.nav-toggle { display: none; }
.nav-toggle-label {
  display: none; cursor: pointer;
  width: 32px; height: 24px; position: relative;
}
.nav-toggle-label span,
.nav-toggle-label span::before,
.nav-toggle-label span::after {
  display: block; background: var(--text); height: 2px; width: 100%;
  border-radius: 2px; position: absolute; transition: transform .3s, opacity .3s;
}
.nav-toggle-label span { top: 50%; transform: translateY(-50%); }
.nav-toggle-label span::before { content: ''; top: -8px; }
.nav-toggle-label span::after { content: ''; top: 8px; }
.nav-toggle:checked + .nav-toggle-label span { background: transparent; }
.nav-toggle:checked + .nav-toggle-label span::before { top: 0; transform: rotate(45deg); background: var(--text); }
.nav-toggle:checked + .nav-toggle-label span::after { top: 0; transform: rotate(-45deg); background: var(--text); }

/* Responsive */
@media (max-width: 700px) {
  .hero h1 { font-size: 1.5rem; }
  h2 { font-size: 1.25rem; }
  table { font-size: .78rem; }
  th, td { padding: .4rem .5rem; }

  .nav-toggle-label { display: block; }

  header .container { flex-wrap: wrap; }

  nav {
    display: none; flex-direction: column; width: 100%;
    padding: .5rem 0; gap: .25rem;
    border-top: 1px solid var(--border); margin-top: .5rem;
  }
  nav a { padding: .5rem 0; font-size: .9rem; }
  nav a.lang-switch { margin-left: 0; align-self: flex-start; margin-top: .25rem; }

  .nav-toggle:checked ~ nav { display: flex; }
}

/* Breadcrumb */
.breadcrumb {
  font-size: .8rem; color: var(--text-dim);
  margin-bottom: 1.5rem; padding: .5rem 0;
}
.breadcrumb a { color: var(--text-dim); }
.breadcrumb a:hover { color: #fff; }
.breadcrumb span { margin: 0 .35rem; color: #555; }

/* Active nav link */
nav a.active { color: #fff; background: rgba(255,255,255,.08); }

/* Language switcher */
nav a.lang-switch {
  margin-left: auto;
  font-weight: 600;
  font-size: .75rem;
  text-transform: uppercase;
  letter-spacing: .05em;
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: .25rem .5rem;
  color: var(--text-dim);
}
nav a.lang-switch:hover { color: #fff; border-color: #555; }

/* Card grid for overview pages */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
  margin: 1.5rem 0;
}
a.card {
  display: block;
  transition: border-color .2s, background .2s;
}
a.card:hover {
  border-color: #444;
  background: #1a1a1a;
  text-decoration: none;
}
a.card h3 { font-size: 1rem; margin: 0 0 .5rem; color: #fff; }
a.card p { font-size: .85rem; color: var(--text-dim); margin: 0; }

/* Page title (h1 on subpages) */
.page-title {
  font-size: 1.6rem; font-weight: 700; color: #fff;
  letter-spacing: -.02em; margin-bottom: 1.5rem; line-height: 1.3;
}

/* Sub-navigation */
.sub-nav { margin-top: 2.5rem; padding-top: 1.5rem; border-top: 1px solid var(--border); }
.sub-nav h3 { font-size: .95rem; margin: 0 0 .75rem; color: var(--text-dim); text-transform: uppercase; letter-spacing: .04em; }
.sub-nav a {
  display: inline-block; font-size: .85rem; margin: .15rem .5rem .15rem 0;
  color: var(--text-dim); padding: .25rem .5rem; border: 1px solid var(--border);
  border-radius: 4px; transition: color .2s, border-color .2s;
}
.sub-nav a:hover { color: #fff; border-color: #555; text-decoration: none; }
.sub-nav a.current { color: #fff; border-color: #555; pointer-events: none; }

/* Schema / SEO hidden */
.sr-only {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0,0,0,0); border: 0;
}