/* ==========================================================================
   CUVCPE — Dual-layer design system
   Layer 1: Contemporary / Exploratory (entry)
   Layer 2: Academic / Structured (rest of site)
   Cambridge-inspired palette; editorial typography; calm transitions
   ========================================================================== */

:root {
  /* Cambridge & logo-aligned palette */
  --cam-blue: #8EE8D8;
  --cam-light-blue: #D1F9F1;
  --cam-warm-blue: #00BDB6;
  --cam-dark-blue: #133844;
  --crest: #FD8153;
  --crest-dark: #DD3025;
  --slate-1: #ECEEF1;
  --slate-2: #B5BDC8;
  --slate-3: #546072;
  --slate-4: #232830;
  --white: #FFFFFF;
  --bg-subtle: #F8FAFA;
  --bg-layer2: #FAFCFC;

  /* Typography */
  --font-display: 'Cormorant Garamond', Georgia, serif;
  --font-body: 'Source Sans 3', system-ui, sans-serif;

  /* Spacing & rhythm */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  --space-2xl: 4rem;
  --space-3xl: 6rem;
  --section-padding: clamp(3rem, 8vw, 5rem);
  --container: min(90vw, 72rem);

  /* Motion */
  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --duration: 0.4s;
}

/* Reset & base */
*, *::before, *::after { box-sizing: border-box; }
html {
  scroll-behavior: smooth;
}
body {
  margin: 0;
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.6;
  color: var(--slate-4);
  background: var(--white);
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; height: auto; display: block; }
a { color: var(--cam-dark-blue); text-decoration: none; transition: color var(--duration) var(--ease-out); }
a:hover { color: var(--crest-dark); }
ul { list-style: none; margin: 0; padding: 0; }

/* ==========================================================================
   Site header — minimal, works in both layers
   ========================================================================== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: var(--space-md) var(--space-lg);
  background: transparent;
  transition: background var(--duration) var(--ease-out), box-shadow var(--duration) var(--ease-out);
}
.site-header.scrolled {
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(8px);
  box-shadow: 0 1px 0 var(--slate-1);
}
.header-inner {
  max-width: var(--container);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  color: var(--slate-4);
  font-weight: 600;
  font-size: 1rem;
  letter-spacing: 0.02em;
}
.logo:hover { color: var(--slate-4); }
.logo img { width: 40px; height: 40px; border-radius: 4px; }
.nav ul { display: flex; gap: var(--space-lg); }
.nav a {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--slate-3);
}
.nav a:hover { color: var(--cam-dark-blue); }
.nav-toggle {
  display: none;
  width: 2rem;
  height: 2rem;
  padding: 0;
  border: none;
  background: transparent;
  cursor: pointer;
  position: relative;
}
.nav-toggle::before,
.nav-toggle::after {
  content: '';
  position: absolute;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--slate-4);
  transition: transform var(--duration) var(--ease-out);
}
.nav-toggle::before { top: 0.4rem; }
.nav-toggle::after { bottom: 0.4rem; }
.nav-toggle[aria-expanded="true"]::before { transform: translateY(0.5rem) rotate(45deg); }
.nav-toggle[aria-expanded="true"]::after { transform: translateY(-0.5rem) rotate(-45deg); }

/* ==========================================================================
   LAYER 1 — Entry (Contemporary / Exploratory)
   ========================================================================== */
.entry {
  position: relative;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: var(--space-3xl) var(--space-lg);
  overflow: hidden;
}
.entry-bg {
  position: absolute;
  inset: 0;
  background: linear-gradient(165deg, var(--bg-subtle) 0%, var(--cam-light-blue) 35%, var(--white) 70%);
  opacity: 0.95;
}
.entry-bg::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(circle at 20% 30%, rgba(142, 232, 216, 0.15) 0%, transparent 45%),
    radial-gradient(circle at 80% 70%, rgba(0, 189, 182, 0.08) 0%, transparent 40%);
  pointer-events: none;
}
.entry-content {
  position: relative;
  z-index: 1;
  text-align: center;
  max-width: 36rem;
}
.entry-label {
  font-family: var(--font-body);
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--slate-3);
  margin: 0 0 var(--space-md);
}
.entry-title {
  font-family: var(--font-display);
  font-size: clamp(2.25rem, 5vw, 3.5rem);
  font-weight: 600;
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--slate-4);
  margin: 0 0 var(--space-lg);
}
.entry-mission {
  font-size: 1.125rem;
  line-height: 1.65;
  color: var(--slate-3);
  margin: 0 0 var(--space-xl);
  font-weight: 400;
}
.cta {
  display: inline-block;
  padding: 0.875rem 1.75rem;
  font-family: var(--font-body);
  font-size: 0.9375rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  border-radius: 4px;
  transition: background var(--duration) var(--ease-out), color var(--duration) var(--ease-out), border-color var(--duration) var(--ease-out);
}
.cta-primary {
  background: var(--cam-dark-blue);
  color: var(--white);
  border: 2px solid var(--cam-dark-blue);
}
.cta-primary:hover {
  background: var(--slate-4);
  border-color: var(--slate-4);
  color: var(--white);
}
.entry-scroll {
  position: absolute;
  bottom: var(--space-xl);
  left: 50%;
  transform: translateX(-50%);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--slate-2);
}

/* ==========================================================================
   LAYER 2 — Structured sections (Academic / Calm)
   ========================================================================== */
.section {
  padding: var(--section-padding) var(--space-lg);
  background: var(--white);
}
.section--structured {
  background: var(--bg-layer2);
}
.section--structured:nth-child(even) {
  background: var(--white);
}
.container {
  max-width: var(--container);
  margin: 0 auto;
}
.section-head {
  max-width: 42rem;
  margin-bottom: var(--space-2xl);
}
.section-title {
  font-family: var(--font-display);
  font-size: clamp(1.75rem, 3vw, 2.25rem);
  font-weight: 600;
  color: var(--slate-4);
  margin: 0 0 var(--space-md);
}
.section-lead {
  font-size: 1.125rem;
  line-height: 1.65;
  color: var(--slate-3);
  margin: 0;
}

/* The Society — cards */
.society-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr));
  gap: var(--space-lg);
}
.society-card {
  padding: var(--space-lg);
  background: var(--white);
  border-radius: 6px;
  border: 1px solid var(--slate-1);
  transition: border-color var(--duration) var(--ease-out), box-shadow var(--duration) var(--ease-out);
}
.society-card:hover {
  border-color: var(--slate-2);
  box-shadow: 0 4px 20px rgba(35, 40, 48, 0.06);
}
.society-card h3 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 600;
  margin: 0 0 var(--space-sm);
  color: var(--slate-4);
}
.society-card p {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--slate-3);
  line-height: 1.6;
}

/* Knowledge Pillars */
.pillars {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-md);
  margin-bottom: var(--space-2xl);
}
.pillar {
  text-align: center;
  padding: var(--space-lg) var(--space-md);
  background: var(--white);
  border-radius: 6px;
  border: 1px solid var(--slate-1);
}
.pillar-icon {
  width: 3rem;
  height: 3rem;
  margin: 0 auto var(--space-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.875rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--white);
  background: var(--cam-dark-blue);
  border-radius: 4px;
}
.pillar h3 {
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 600;
  margin: 0 0 var(--space-xs);
  color: var(--slate-4);
}
.pillar p {
  margin: 0;
  font-size: 0.875rem;
  color: var(--slate-3);
  line-height: 1.55;
}
.activities {
  padding: var(--space-lg) 0;
  border-top: 1px solid var(--slate-1);
}
.activities-title {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 600;
  margin: 0 0 var(--space-md);
  color: var(--slate-4);
}
.activities-list li {
  padding: var(--space-xs) 0;
  font-size: 0.9375rem;
  color: var(--slate-3);
  padding-left: 1.25rem;
  position: relative;
}
.activities-list li::before {
  content: '—';
  position: absolute;
  left: 0;
  color: var(--cam-warm-blue);
}

/* Academic Timeline */
.timeline-track {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}
.timeline-item {
  padding: var(--space-lg);
  background: var(--white);
  border-radius: 6px;
  border-left: 3px solid var(--cam-warm-blue);
  box-shadow: 0 1px 0 var(--slate-1);
}
.timeline-term {
  display: block;
  font-weight: 600;
  font-size: 0.9375rem;
  color: var(--cam-dark-blue);
  margin-bottom: var(--space-sm);
}
.timeline-item p {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--slate-3);
  line-height: 1.6;
}

/* Community */
.community-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(18rem, 1fr));
  gap: var(--space-xl);
  margin-bottom: var(--space-xl);
}
.community-block h3 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 600;
  margin: 0 0 var(--space-sm);
  color: var(--slate-4);
}
.community-block p {
  margin: 0;
  color: var(--slate-3);
  line-height: 1.6;
}
.cta-secondary {
  background: transparent;
  color: var(--cam-dark-blue);
  border: 2px solid var(--cam-dark-blue);
}
.cta-secondary:hover {
  background: var(--cam-dark-blue);
  color: var(--white);
}
.cta-outline {
  background: transparent;
  color: var(--slate-3);
  border: 2px solid var(--slate-2);
}
.cta-outline:hover {
  border-color: var(--slate-4);
  color: var(--slate-4);
}

/* Partnerships */
.partners-highlights {
  padding: var(--space-lg) 0;
}
.highlights-title {
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 600;
  margin: 0 0 var(--space-md);
  color: var(--slate-4);
}
.partners-list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
  margin-bottom: var(--space-lg);
}
.partners-list li {
  padding: var(--space-sm) var(--space-md);
  background: var(--white);
  border: 1px solid var(--slate-1);
  border-radius: 4px;
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--slate-4);
}
.partners-note {
  font-size: 0.9375rem;
  color: var(--slate-3);
  line-height: 1.6;
  margin: 0;
  max-width: 40rem;
}

/* Join */
.join-head { margin-bottom: var(--space-xl); }
.join-actions p {
  margin: 0 0 var(--space-lg);
  color: var(--slate-3);
  max-width: 36rem;
}
.join-actions .cta { margin-right: var(--space-sm); margin-bottom: var(--space-sm); }

/* Contact */
.contact-details { padding: var(--space-md) 0; }
.contact-email {
  font-size: 1.25rem;
  font-weight: 600;
  margin: 0 0 var(--space-sm);
}
.contact-email a { color: var(--cam-dark-blue); }
.contact-meta {
  font-size: 0.9375rem;
  color: var(--slate-3);
  margin: 0;
  line-height: 1.6;
}

/* Footer */
.site-footer {
  padding: var(--space-xl) var(--space-lg);
  background: var(--slate-4);
  color: var(--slate-2);
}
.footer-inner {
  max-width: var(--container);
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-lg);
}
.logo-footer {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  color: var(--white);
  font-weight: 600;
  font-size: 0.9375rem;
}
.logo-footer:hover { color: var(--cam-light-blue); }
.footer-tagline {
  font-size: 0.875rem;
  margin: 0;
  flex: 1;
  min-width: 12rem;
}
.footer-nav {
  display: flex;
  gap: var(--space-lg);
}
.footer-nav a {
  color: var(--slate-2);
  font-size: 0.9375rem;
}
.footer-nav a:hover { color: var(--white); }

/* ==========================================================================
   Responsive — mobile first adjustments
   ========================================================================== */
@media (max-width: 900px) {
  .pillars { grid-template-columns: repeat(2, 1fr); }
  .timeline-track { grid-template-columns: 1fr; }
}

@media (max-width: 700px) {
  .nav { display: none; }
  .nav.open { display: block; position: absolute; top: 100%; left: 0; right: 0; background: var(--white); padding: var(--space-lg); box-shadow: 0 4px 20px rgba(0,0,0,0.08); }
  .nav.open ul { flex-direction: column; gap: var(--space-md); }
  .nav-toggle { display: block; }
  .pillars { grid-template-columns: 1fr; }
  .footer-inner { flex-direction: column; align-items: flex-start; }
}

@media (max-width: 480px) {
  .entry { padding: var(--space-2xl) var(--space-md); }
  .section { padding: var(--space-2xl) var(--space-md); }
  .join-actions .cta { display: block; margin-right: 0; }
}