/* =============================================================================
   Base Variables & Reset (from home.css + necessary legacy variables)
   ============================================================================= */
:root {
  /* Core Palette */
  --color-bg: #F9F9F6;
  --color-bg-alt: #FFFFFF;
  --color-text: #333333;
  --color-primary: #2E5EAA;
  --color-accent: #F9C74F;
  --color-warm: #F9844A;
  --color-highlight: #4CAF50;

  /* DNA Bases */
  --color-adenine: #4CAF50;
  --color-thymine: #E63946;
  --color-cytosine: #457B9D;
  --color-guanine: #F1C40F;

  /* Typography */
  --font-body: system-ui, -apple-system, sans-serif;
  --text-size: 16px;
  --line-height: 1.6;

  /* Legacy internal-page palette */
  --base-a: #4CAF50;
  --base-t: #F44336;
  --base-c: #2196F3;
  --base-g: #FFEB3B;
  --backbone: #F5F5F5;
  --bond: #BDBDBD;
  --accent-2: var(--base-c);
  --line: #ddd;
  --card: #ffffff;
  --shadow: rgba(0, 0, 0, 0.08);
  --maxw: 1080px;
}

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

body {
  font-family: var(--font-body);
  font-size: var(--text-size);
  line-height: var(--line-height);
  color: var(--color-text);
  background: var(--color-bg);
}

/* =============================================================================
   Container & Header (home.css)
   ============================================================================= */
.container,
.wrap {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 1rem;
}

.header .container {
  text-align: center;
}

.header .site-title {
  font-size: clamp(1.75rem, 6vw, 2.5rem);
  font-weight: 700;
  color: var(--color-cytosine);
  margin: 1.5rem 0;
}

/* =============================================================================
   Navigation — Bubble Style (home.css)
   ============================================================================= */
.topnav {
  background: var(--color-bg);
  position: sticky;
  top: 0;
  z-index: 1000;
  border-bottom: 1px solid rgba(0,0,0,0.1);
  box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.topnav .wrap {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px 24px;
  padding: 0.75rem 1rem;
}

.topnav a {
  display: inline-block;
  padding: 10px 16px;
  font-size: 1rem;
  font-weight: 600;
  border-radius: 999px;
  background: rgba(46, 94, 170, 0.05);
  color: var(--color-primary);
  text-shadow: 0 0 4px rgba(46,94,170,0.3);
  transition: transform 0.3s ease,
              background 0.3s ease,
              color 0.3s ease,
              text-shadow 0.3s ease;
}

.topnav a:hover,
.topnav a.active {
  background: var(--color-accent);
  color: var(--color-text);
  text-shadow: 0 0 6px var(--color-accent);
  transform: scale(1.05);
}

/* =============================================================================
   Hero Section (home.css)
   ============================================================================= */
.hero {
  position: relative;
  text-align: center;
  color: #fff;
  background: linear-gradient(135deg,
    var(--color-primary) 0%,
    var(--color-highlight) 100%);
  padding: 80px 0;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,0.25);
}

.hero .container {
  position: relative;
  z-index: 1;
}

.hero__title {
  font-size: clamp(32px, 5vw, 56px);
  font-weight: 700;
  margin-bottom: 1rem;
}

.hero__lede {
  font-family: var(--font-body);
  font-size: 1.3rem;
  font-weight: 600;
  line-height: 1.8;
  max-width: 700px;
  margin: 0 auto 2rem;
  color: var(--color-thymine);
  text-shadow: 0 2px 4px rgba(0,0,0,0.5);
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem 1rem;
}

.hero__actions .btn {
  min-width: 10rem;
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
}

/* =============================================================================
   Global Button Styles (home.css)
   ============================================================================= */
.btn {
  display: inline-block;
  border-radius: 6px;
  font-weight: 600;
  text-decoration: none;
  text-align: center;
  transition: background 0.2s ease,
              color 0.2s ease;
}

.btn--primary {
  background: var(--color-accent);
  color: var(--color-text);
}
.btn--primary:hover {
  background: var(--color-warm);
  color: #fff;
}

.btn--secondary {
  background: var(--color-guanine);
  color: var(--color-text);
}
.btn--secondary:hover {
  background: var(--color-thymine);
  color: #fff;
}

.btn--ghost {
  background: transparent;
}

.hero .btn--ghost {
  border: 2px solid #fff;
  color: #fff;
}
.hero .btn--ghost:hover {
  background: rgba(255,255,255,0.2);
}

.section .btn--ghost {
  border: 2px solid var(--color-primary);
  color: var(--color-primary);
}
.section .btn--ghost:hover {
  background: var(--color-primary);
  color: #fff;
}

/* =============================================================================
   Sections & Rhythm (home.css)
   ============================================================================= */
.section {
  max-width: var(--maxw);
  margin: 2rem auto;
  padding: 3rem 1.5rem;
}

.section:nth-of-type(odd) {
  background: var(--color-bg);
}

.section:nth-of-type(even) {
  background: var(--color-bg-alt);
}

.section h2 {
  color: var(--color-primary);
  margin-bottom: 1rem;
}

.section p,
.section ul {
  margin-bottom: 1rem;
}

.section ul {
  list-style: disc inside;
  padding-left: 1rem;
}

/* =============================================================================
   Footer (home.css)
   ============================================================================= */
.footer {
  text-align: center;
  padding: 2rem 1rem;
  background: var(--color-bg);
  border-top: 1px solid rgba(0,0,0,0.1);
  font-size: 0.9rem;
  color: rgba(0,0,0,0.7);
}

/* =============================================================================
   Internal‐Page Styles (legacy main.css scoped to .internal-page)
   ============================================================================= */
.internal-page a {
  color: var(--accent-2);
}
.internal-page a:hover {
  text-decoration: underline;
}

.internal-page header,
.internal-page main,
.internal-page footer {
  width: 100%;
}

.internal-page .hero {
  padding: 56px 0 24px;
  display: grid;
  gap: 24px;
  align-items: center;
  background: none;
  color: var(--color-text);
}
.internal-page .hero h1 {
  font-size: clamp(28px, 4vw, 44px);
  margin: 0;
  line-height: 1.15;
  letter-spacing: 0.2px;
  color: var(--base-a);
}
.internal-page .hero p.subhead {
  margin: 0;
  color: var(--base-c);
  font-size: clamp(16px, 2.2vw, 20px);
}
.internal-page .hero .media {
  margin-top: 12px;
  border: 1px solid var(--line);
  background: var(--card);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 10px 30px var(--shadow);
}
.internal-page .hero .media img {
  width: 100%;
  height: auto;
  display: block;
}

.internal-page .pull {
  padding: 14px 16px;
  border-left: 3px solid var(--base-t);
  background: #fbeaea;
  color: var(--color-text);
  border-radius: 6px;
  margin: 8px 0 0;
  font-style: italic;
}

.internal-page nav.breadcrumbs {
  margin-top: 12px;
  color: var(--muted);
  font-size: 0.9rem;
}
.internal-page nav.breadcrumbs a {
  color: var(--muted);
}

.internal-page section {
  padding: 28px 0;
  border-top: 1px solid var(--line);
}
.internal-page section:first-of-type {
  border-top: none;
}
.internal-page section:nth-of-type(even) {
  background: var(--backbone);
}

.internal-page h2 {
  font-size: clamp(22px, 3vw, 32px);
  margin: 0 0 6px;
  color: var(--base-c);
}
.internal-page h3 {
  font-size: clamp(18px, 2.2vw, 22px);
  margin: 14px 0 6px;
}

.internal-page p {
  margin: 10px 0 0;
  color: var(--color-text);
}

.internal-page .grid {
  display: grid;
  gap: 18px;
}
@media (min-width: 900px) {
  .internal-page .grid.two {
    grid-template-columns: 1fr 1fr;
    align-items: start;
  }
}

.internal-page .card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 16px;
  box-shadow: 0 10px 20px var(--shadow);
}

.internal-page ul,
.internal-page ol {
  margin: 10px 0 0 18px;
}
.internal-page li {
  margin: 8px 0;
}

.internal-page .fact {
  background: #f5f9ff;
  border: 1px solid #dce6f5;
  border-radius: 10px;
  padding: 14px 16px;
}

.internal-page .kbd {
  background: var(--code);
  padding: 2px 6px;
  border-radius: 6px;
  border: 1px solid #ccc;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.95em;
}

.internal-page .cta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 14px;
}
.internal-page .btn {
  display: inline-block;
  padding: 10px 14px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: #f0f0f0;
  color: var(--color-text);
  text-decoration: none;
}
.internal-page .btn.primary {
  background: linear-gradient(180deg, var(--base-c), var(--accent-2));
  border-color: var(--accent-2);
  color: #fff;
}

.internal-page .small {
  font-size: 14px;
  color: var(--muted);
}
.internal-page footer {
  background: var(--backbone);
  border-top: 1px solid var(--bond);
  padding-top: 1rem;
  color: var(--muted);
}
.internal-page footer .links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 6px;
}

/* DNA rhythm & semantic roles (internal pages) */
.internal-page .pair {
  display: flex;
  flex-wrap: wrap;
  gap: 2rem;
  align-items: center;
  padding: 2rem 0;
}
.internal-page .pair:nth-of-type(even) {
  flex-direction: row-reverse;
  background: var(--backbone);
}

.internal-page .bond {
  border-top: 1px dashed var(--bond);
  margin: 2rem 0;
}

.internal-page .helix {
  background: linear-gradient(
    to right,
    var(--base-a),
    var(--base-t),
    var(--base-c),
    var(--base-g)
  );
  -webkit-background-clip: text;
  color: transparent;
  font-weight: 700;
  font-size: 1.2rem;
  letter-spacing: 0.5px;
}

.internal-page .signal { color: var(--base-t); }
.internal-page .invitation { color: var(--base-g); }
.internal-page .pillar { color: var(--base-c); }
.internal-page .scaffold { background: var(--backbone); }