/* ===== PHYSICS FUNDAMENTALS INFO - SHARED STYLESHEET ===== */
/* This file is shared across all pages for fast caching */

:root {
  --ink: #0A1628;
  --ink-2: #142139;
  --ink-3: #1F2E47;
  --cream: #FAF6EE;
  --paper: #F5F2EA;
  --gold: #C8932A;
  --gold-bright: #E8B43D;
  --gold-soft: #F4E8D0;
  --gold-text: #7E5B11;     /* WCAG AA on cream/paper backgrounds */
  --bronze: #8B6914;
  --wine: #7A1F2B;
  --mist: #C5D0DC;
  --mist-2: #8597AF;
  --mist-text: #5A6D85;     /* WCAG AA on cream/paper backgrounds */
  --rule: #D9CFB8;
  --shadow: 0 30px 60px rgba(10, 22, 40, 0.12);
  --shadow-deep: 0 40px 80px rgba(10, 22, 40, 0.25);
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: 'Manrope', -apple-system, sans-serif;
  color: var(--ink);
  background: var(--cream);
  line-height: 1.6;
  font-size: 17px;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
button { font-family: inherit; cursor: pointer; }

.serif { font-family: 'Spectral', Georgia, serif; }
.mono { font-family: 'JetBrains Mono', monospace; }
h1, h2, h3, h4 {
  font-family: 'Spectral', Georgia, serif;
  font-weight: 600;
  letter-spacing: -0.015em;
  line-height: 1.15;
  margin: 0 0 0.5em;
}
.eyebrow {
  font-family: 'Manrope', sans-serif;
  font-size: 12px;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  font-weight: 700;
  color: var(--gold-text);
}

.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }
.container-narrow { max-width: 880px; margin: 0 auto; padding: 0 24px; }
section { padding: 100px 0; position: relative; }
@media (max-width: 768px) { section { padding: 64px 0; } }

/* ===== NAVIGATION ===== */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(250, 246, 238, 0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--rule);
}
.nav-inner {
  display: flex; align-items: center; justify-content: space-between;
  padding: 18px 24px; max-width: 1200px; margin: 0 auto;
}
.logo {
  display: flex; align-items: center; gap: 12px;
  font-family: 'Spectral', Georgia, serif;
  font-size: 22px; font-weight: 700; color: var(--ink);
  letter-spacing: -0.02em;
}
.logo-mark { width: 36px; height: 36px; flex-shrink: 0; }
.nav-links {
  display: flex; gap: 30px; align-items: center;
  font-size: 14px; font-weight: 500;
}
.nav-links a { color: var(--ink-3); transition: color 0.15s; }
.nav-links a:hover { color: var(--gold); }
.nav-cta {
  background: var(--ink); color: var(--cream);
  padding: 10px 20px; border-radius: 2px; font-size: 13px;
  font-weight: 600; letter-spacing: 0.05em; text-transform: uppercase;
  border: none; transition: all 0.15s;
}
.nav-cta:hover { background: var(--wine); }
.mobile-toggle {
  display: none; background: none; border: none;
  color: var(--ink); cursor: pointer; padding: 8px;
}
@media (max-width: 1024px) {
  .nav-links { display: none; }
  .mobile-toggle { display: block; }
  .nav-cta { display: none; }
  .nav-links.mobile-open {
    display: flex; flex-direction: column;
    position: absolute; top: 100%; left: 0; right: 0;
    background: var(--cream); padding: 24px;
    border-bottom: 1px solid var(--rule);
    gap: 20px;
  }
}

/* ===== BUTTONS ===== */
.btn-primary {
  background: var(--gold); color: var(--ink);
  padding: 16px 32px; border-radius: 2px; font-size: 14px;
  font-weight: 700; letter-spacing: 0.1em; text-transform: uppercase;
  border: none; transition: all 0.2s;
  display: inline-flex; align-items: center; gap: 10px;
}
.btn-primary:hover {
  background: var(--gold-bright);
  transform: translateY(-2px);
  box-shadow: 0 10px 30px rgba(200, 147, 42, 0.4);
}
.btn-secondary {
  background: transparent; color: var(--cream);
  padding: 16px 32px; border-radius: 2px; font-size: 14px;
  font-weight: 700; letter-spacing: 0.1em; text-transform: uppercase;
  border: 1px solid rgba(245, 242, 234, 0.3); transition: all 0.2s;
  display: inline-flex; align-items: center; gap: 10px;
}
.btn-secondary:hover {
  background: rgba(245, 242, 234, 0.08);
  border-color: var(--cream);
}

/* ===== PAGE HEADER (used on subpages) ===== */
.page-header {
  background: var(--ink);
  color: var(--cream);
  padding: 100px 0 80px;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.page-header h1 {
  font-size: clamp(36px, 5vw, 60px);
  margin: 16px auto;
  max-width: 800px;
}
.page-header h1 em { font-style: italic; color: var(--gold); }
.page-header p {
  font-size: 18px; color: var(--mist); max-width: 640px;
  margin: 0 auto; line-height: 1.6;
}
.page-header .eyebrow {
  display: inline-block;
  padding: 6px 14px; border: 1px solid rgba(200, 147, 42, 0.4);
  border-radius: 999px;
}

/* ===== BREADCRUMBS ===== */
.breadcrumbs {
  background: var(--paper);
  padding: 14px 0;
  border-bottom: 1px solid var(--rule);
  font-size: 13px;
  color: var(--ink-3);
}
.breadcrumbs a { color: var(--ink-3); transition: color 0.15s; }
.breadcrumbs a:hover { color: var(--gold); }
.breadcrumbs .sep { color: var(--mist-2); margin: 0 8px; }
.breadcrumbs .current { color: var(--gold); font-weight: 600; }

/* ===== PROSE (article body) ===== */
.prose {
  font-size: 17px;
  line-height: 1.75;
  color: var(--ink);
}
.prose h2 {
  font-size: 32px;
  margin-top: 64px;
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--gold);
  display: inline-block;
}
.prose h3 {
  font-size: 24px;
  margin-top: 40px;
  margin-bottom: 16px;
}
.prose p { margin: 0 0 22px; }
.prose ul, .prose ol { margin: 0 0 22px; padding-left: 24px; }
.prose li { margin-bottom: 10px; }
.prose strong { color: var(--wine); }
.prose a { color: var(--gold-text); border-bottom: 1px solid currentColor; }
.prose a:hover { color: var(--wine); }
.prose blockquote {
  border-left: 4px solid var(--gold);
  padding: 8px 24px;
  margin: 32px 0;
  background: var(--paper);
  font-family: 'Spectral', serif;
  font-style: italic;
  font-size: 19px;
  color: var(--ink-3);
}

/* ===== FOOTER ===== */
footer {
  background: var(--ink);
  color: var(--mist);
  padding: 80px 0 32px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: 60px;
  margin-bottom: 60px;
}
@media (max-width: 900px) {
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 40px; }
}
@media (max-width: 540px) {
  .footer-grid { grid-template-columns: 1fr; gap: 32px; }
}
.footer-brand .logo { color: var(--cream); margin-bottom: 16px; }
.footer-brand p {
  font-size: 14px; line-height: 1.6;
  max-width: 320px;
}
.footer-col h3 {
  font-family: 'Manrope', sans-serif;
  font-size: 11px; letter-spacing: 0.18em; text-transform: uppercase;
  font-weight: 700; color: var(--cream);
  margin-bottom: 20px;
}
.footer-col ul {
  list-style: none; padding: 0; margin: 0;
  display: flex; flex-direction: column; gap: 10px;
}
.footer-col a {
  color: var(--mist); font-size: 14px;
  transition: color 0.15s;
}
.footer-col a:hover { color: var(--gold); }
.footer-bottom {
  padding-top: 32px;
  border-top: 1px solid rgba(197, 208, 220, 0.1);
  display: flex; justify-content: space-between; align-items: center;
  flex-wrap: wrap; gap: 16px;
  font-size: 12px; color: var(--mist-2);
  letter-spacing: 0.04em;
}
.footer-social {
  display: flex; gap: 12px;
}
.footer-social a {
  width: 36px; height: 36px;
  border: 1px solid rgba(197, 208, 220, 0.2);
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  transition: all 0.15s;
}
.footer-social a:hover {
  border-color: var(--gold);
  color: var(--gold);
}

/* ===== ANIMATIONS ===== */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}
.fade-up { animation: fadeUp 0.8s ease-out backwards; }

/* ===== ACCESSIBILITY: respect reduced-motion ===== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}