/* ==========================================================================
   Neuro Serge — Design System
   Clean, dependency-free CSS. No framework.
   ========================================================================== */

:root {
  --navy-950: #0a2340;
  --navy-900: #0b2f5e;
  --navy-800: #123b73;
  --blue-600: #1f6fd6;
  --blue-500: #2f8ce8;
  --teal-500: #17a8a0;
  --teal-100: #e3f6f4;
  --ink-900: #16202c;
  --ink-700: #3b4a5a;
  --ink-500: #64748b;
  --line-200: #e3e8ef;
  --line-100: #eef1f6;
  --bg-canvas: #ffffff;
  --bg-alt: #f6f9fc;
  --bg-navy-tint: #eef4fb;
  --gold-600: #b8862c;
  --amber-100: #fff6e6;
  --amber-400: #e6a622;
  --danger-600: #b3261e;
  --success-700: #1b7a4a;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-full: 999px;
  --shadow-sm: 0 1px 2px rgba(16, 32, 55, 0.06), 0 1px 1px rgba(16, 32, 55, 0.04);
  --shadow-md: 0 8px 24px rgba(16, 32, 55, 0.08);
  --shadow-lg: 0 20px 48px rgba(16, 32, 55, 0.12);
  --max-width: 1180px;
  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-display: "Source Serif 4", Georgia, "Times New Roman", serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

html, body { max-width: 100%; overflow-x: hidden; }
body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--ink-900);
  background: var(--bg-canvas);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

a { color: var(--blue-600); }
a:focus-visible,
button:focus-visible,
input:focus-visible,
summary:focus-visible,
[tabindex]:focus-visible {
  outline: 3px solid var(--teal-500);
  outline-offset: 2px;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--navy-950);
  line-height: 1.2;
  margin: 0 0 0.6em;
  font-weight: 700;
}
h1 { font-size: clamp(2rem, 1.5rem + 2vw, 3rem); }
h2 { font-size: clamp(1.5rem, 1.2rem + 1.2vw, 2.1rem); }
h3 { font-size: clamp(1.2rem, 1.05rem + 0.6vw, 1.5rem); }
h4 { font-size: 1.1rem; }
p { margin: 0 0 1em; color: var(--ink-700); }
p:last-child { margin-bottom: 0; }

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--navy-900);
  color: #fff;
  padding: 0.75rem 1.25rem;
  z-index: 1000;
  border-radius: 0 0 8px 0;
}
.skip-link:focus { left: 0; }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}
.container--narrow { max-width: 860px; }

section { padding: 4.5rem 0; }
@media (max-width: 640px) {
  section { padding: 3rem 0; }
}
.section-alt { background: var(--bg-alt); }
.section-navy {
  background: linear-gradient(160deg, var(--navy-950), var(--navy-800));
  color: #eaf1fb;
}
.section-navy h2, .section-navy h3 { color: #fff; }
.section-navy p { color: #c7d7ea; }

.eyebrow {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--teal-500);
  margin-bottom: 0.75rem;
}
.section-head {
  max-width: 760px;
  margin: 0 auto 2.75rem;
  text-align: center;
}
.section-head p { font-size: 1.05rem; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.85rem 1.6rem;
  border-radius: var(--radius-full);
  font-weight: 700;
  text-decoration: none;
  font-size: 1rem;
  border: 2px solid transparent;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
  line-height: 1.1;
}
.btn:hover { transform: translateY(-1px); }
.btn-primary {
  background: var(--teal-500);
  color: #fff;
  box-shadow: var(--shadow-md);
}
.btn-primary:hover { background: #12958e; color: #fff; }
.btn-outline {
  background: transparent;
  border-color: rgba(255,255,255,0.6);
  color: #fff;
}
.btn-outline:hover { background: rgba(255,255,255,0.12); color: #fff; }
.btn-navy {
  background: var(--navy-900);
  color: #fff;
}
.btn-navy:hover { background: var(--navy-950); color: #fff; }
.btn-ghost {
  background: transparent;
  border-color: var(--line-200);
  color: var(--navy-900);
}
.btn-ghost:hover { border-color: var(--navy-900); }
.btn-sm { padding: 0.55rem 1.1rem; font-size: 0.9rem; }
.btn-block { width: 100%; }

/* ---------- Header / nav ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.94);
  backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid var(--line-100);
}
.nav-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  padding: 0.75rem 0;
}
.brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  color: var(--navy-950);
  font-weight: 800;
  font-size: 1.15rem;
  font-family: var(--font-display);
}
.brand img { height: 2.4rem; width: auto; }
.nav-links {
  display: flex;
  gap: 1.6rem;
  list-style: none;
  margin: 0;
  padding: 0;
  flex-wrap: wrap;
}
.nav-links a {
  color: var(--ink-700);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
}
.nav-links a:hover { color: var(--navy-900); }
.nav-cta { display: flex; align-items: center; gap: 1rem; }
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  width: 2.6rem;
  height: 2.6rem;
  flex-shrink: 0;
  background: none;
  border: 1px solid var(--line-200);
  border-radius: 8px;
  padding: 0;
  cursor: pointer;
}
.nav-toggle span {
  display: block;
  width: 1.2rem;
  height: 2px;
  background: var(--navy-950);
  border-radius: 1px;
  transition: transform 0.2s ease, opacity 0.2s ease;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

@media (max-width: 880px) {
  .nav-links { display: none; }
  .nav-links.is-open {
    display: flex;
    flex-direction: column;
    gap: 0;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: #fff;
    border-top: 1px solid var(--line-100);
    border-bottom: 1px solid var(--line-100);
    box-shadow: var(--shadow-md);
    padding: 0.5rem 1.5rem 1rem;
  }
  .nav-links.is-open li { width: 100%; }
  .nav-links.is-open a { display: block; padding: 0.85rem 0.25rem; border-bottom: 1px solid var(--line-100); }
  .nav-toggle { display: inline-flex; }
  .nav-cta .btn span.long { display: none; }
}

/* ---------- Hero ---------- */
.hero {
  padding: 3.5rem 0 4rem;
  background: radial-gradient(1100px 480px at 80% -10%, var(--bg-navy-tint), var(--bg-canvas) 60%);
}
.hero-grid {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 3rem;
  align-items: center;
}
@media (max-width: 900px) {
  .hero-grid { grid-template-columns: 1fr; }
  .hero-grid .hero-media { order: -1; max-width: 320px; margin: 0 auto; }
}
.hero-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
  margin: 1.4rem 0 1.8rem;
  padding: 0;
  list-style: none;
}
.hero-badges li {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--ink-700);
}
.hero-badges li::before {
  content: "✓";
  color: var(--teal-500);
  font-weight: 800;
}
.hero-ctas { display: flex; flex-wrap: wrap; gap: 0.9rem; margin-top: 1.6rem; }
.hero-media {
  background: var(--bg-navy-tint);
  border-radius: var(--radius-lg);
  padding: 2rem;
}
.hero-note {
  margin-top: 1rem;
  font-size: 0.85rem;
  color: var(--ink-500);
}

/* ---------- Cards / grids ---------- */
.grid { display: grid; gap: 1.6rem; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 900px) { .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 620px) { .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; } }

.card {
  background: #fff;
  border: 1px solid var(--line-100);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow-sm);
}
.card h3 { margin-bottom: 0.5rem; }
.card-icon {
  width: 3rem;
  height: 3rem;
  border-radius: 12px;
  background: var(--teal-100);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  margin-bottom: 1rem;
}

.ingredient-card { text-align: left; }
.ingredient-card .evidence-tag {
  display: inline-block;
  margin-top: 0.75rem;
  font-size: 0.78rem;
  font-weight: 700;
  padding: 0.25rem 0.7rem;
  border-radius: var(--radius-full);
}
.tag-human { background: #e6f4ea; color: var(--success-700); }
.tag-mixed { background: var(--amber-100); color: #8a5a10; }
.tag-preclinical { background: #eef1f6; color: var(--ink-700); }
.tag-insufficient { background: #fbe9e7; color: var(--danger-600); }

/* ---------- Steps ---------- */
.steps { counter-reset: step; }
.step {
  display: grid;
  grid-template-columns: 3rem 1fr;
  gap: 1rem;
  margin-bottom: 1.5rem;
}
.step-num {
  width: 3rem;
  height: 3rem;
  border-radius: 50%;
  background: var(--navy-900);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-family: var(--font-display);
}

/* ---------- Tables ---------- */
.table-scroll { overflow-x: auto; border-radius: var(--radius-md); border: 1px solid var(--line-200); }
table.evidence-table {
  width: 100%;
  border-collapse: collapse;
  min-width: 720px;
  font-size: 0.94rem;
}
.evidence-table th, .evidence-table td {
  padding: 0.85rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--line-100);
  vertical-align: top;
}
.evidence-table thead th {
  background: var(--navy-900);
  color: #fff;
  font-family: var(--font-display);
  font-weight: 700;
}
.evidence-table tbody tr:nth-child(even) { background: var(--bg-alt); }

/* ---------- Callouts ---------- */
.callout {
  border-radius: var(--radius-lg);
  padding: 1.75rem 2rem;
  border: 1px solid var(--line-200);
  background: var(--bg-alt);
}
.callout-title { display: flex; align-items: center; gap: 0.6rem; font-weight: 800; color: var(--navy-950); margin-bottom: 0.5rem; font-family: var(--font-display); font-size: 1.1rem;}
.callout-warn { background: var(--amber-100); border-color: #f0d9a8; }
.callout-teal { background: var(--teal-100); border-color: #bfe6e2; }

/* ---------- Pricing ---------- */
.pricing-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.5rem; align-items: stretch; }
@media (max-width: 900px) {
  .pricing-grid { grid-template-columns: 1fr; }
  .price-card.featured { transform: none; }
}
.price-card {
  background: #fff;
  border: 1px solid var(--line-200);
  border-radius: var(--radius-lg);
  padding: 2rem 1.6rem;
  text-align: center;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-sm);
}
.price-card.featured {
  border-color: var(--teal-500);
  box-shadow: var(--shadow-lg);
  transform: translateY(-6px);
}
.price-badge {
  display: inline-block;
  background: var(--teal-500);
  color: #fff;
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 0.3rem 0.8rem;
  border-radius: var(--radius-full);
  margin-bottom: 0.75rem;
}
.price-card .supply { color: var(--ink-500); font-size: 0.9rem; margin-bottom: 1.1rem; }
.price-amount { font-family: var(--font-display); font-size: 2.4rem; font-weight: 800; color: var(--navy-950); }
.price-amount span { font-size: 0.95rem; font-weight: 600; color: var(--ink-500); font-family: var(--font-body); }
.price-total { margin: 0.5rem 0 1.3rem; color: var(--ink-700); font-size: 0.9rem; }
.price-total del { color: var(--ink-500); margin-right: 0.4rem; }
.price-card .btn { margin-top: auto; }
.price-fineprint { text-align: center; font-size: 0.85rem; color: var(--ink-500); margin-top: 1.25rem; }

/* ---------- FAQ ---------- */
.faq-item {
  border-bottom: 1px solid var(--line-200);
  padding: 1.1rem 0;
}
.faq-item summary {
  cursor: pointer;
  font-weight: 700;
  color: var(--navy-950);
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  font-size: 1.02rem;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+";
  font-size: 1.4rem;
  color: var(--teal-500);
  flex-shrink: 0;
  line-height: 1;
}
.faq-item[open] summary::after { content: "\2212"; }
.faq-item p { margin-top: 0.9rem; }

/* ---------- Pros / cons ---------- */
.pc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem; }
@media (max-width: 640px) { .pc-grid { grid-template-columns: 1fr; } }
.pc-list { list-style: none; margin: 0; padding: 0; }
.pc-list li { padding-left: 1.6rem; position: relative; margin-bottom: 0.7rem; }
.pc-pro li::before { content: "✓"; position: absolute; left: 0; color: var(--success-700); font-weight: 800; }
.pc-con li::before { content: "•"; position: absolute; left: 0.35rem; color: var(--ink-500); font-weight: 800; }

/* ---------- Breadcrumb ---------- */
.breadcrumb {
  font-size: 0.85rem;
  color: var(--ink-500);
  padding: 1rem 0 0;
}
.breadcrumb a { color: var(--ink-500); text-decoration: none; }
.breadcrumb a:hover { text-decoration: underline; }
.breadcrumb .sep { margin: 0 0.4rem; }

/* ---------- Footer ---------- */
.site-footer {
  background: var(--navy-950);
  color: #c7d7ea;
  padding: 3.5rem 0 2rem;
  margin-top: 4rem;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1fr;
  gap: 2rem;
  margin-bottom: 2.5rem;
}
@media (max-width: 800px) { .footer-grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 480px) { .footer-grid { grid-template-columns: 1fr; } }
.site-footer h4 { color: #fff; font-size: 0.95rem; margin-bottom: 1rem; }
.site-footer ul { list-style: none; margin: 0; padding: 0; }
.site-footer li { margin-bottom: 0.6rem; }
.site-footer a { color: #b7c8de; text-decoration: none; font-size: 0.92rem; }
.site-footer a:hover { color: #fff; }
.footer-disclosure {
  border-top: 1px solid rgba(255,255,255,0.12);
  padding-top: 1.75rem;
  font-size: 0.82rem;
  color: #94a9c4;
}
.footer-disclosure p { color: #94a9c4; }
.footer-bottom {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.5rem;
  font-size: 0.82rem;
  color: #7d93b0;
}

/* ---------- Utility ---------- */
.text-center { text-align: center; }
.mt-0 { margin-top: 0; }
.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}
.legal-content h2 { margin-top: 2rem; }
.legal-content h2:first-child { margin-top: 0; }
.legal-content ul { color: var(--ink-700); }
.back-to-top-space { height: 1px; }

/* ---------- Small-screen polish ---------- */
@media (max-width: 480px) {
  .container { padding: 0 1.25rem; }
  .card, .callout, .price-card { padding: 1.4rem; }
  .hero-ctas, .hero-badges { justify-content: center; text-align: center; }
  .hero-ctas .btn { width: 100%; }
  .pricing-grid .btn { width: 100%; }
  table.evidence-table { min-width: 560px; }
}