/* ==========================================================================
   BHARAT TECHNOLOGY CAPABILITY CENTRE (BTCC)
   common.css — Global Institutional Design System, Header, and Footer
   ========================================================================== */

:root {
  --primary-navy: #0e1b2e;
  --secondary-navy: #152744;
  --accent-gold: #b48332;
  --accent-gold-dark: #996c22;
  --accent-gold-light: #dfb265;
  
  --bg-page: #ffffff;
  --bg-soft-ivory: #faf9f6;
  --bg-card: #ffffff;
  --bg-dark-footer: #0c192c;

  --text-dark: #1e293b;
  --text-muted: #4b5563;
  --text-light-muted: #6b7280;
  --text-blue-link: #0284c7;

  --border-light: #e5e7eb;
  --border-subtle: #f0f2f5;

  --font-serif: 'Playfair Display', Georgia, serif;
  --font-display: 'Cinzel', 'Playfair Display', serif;
  --font-sans: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;

  --site-max-w: 1200px;
}

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

html {
  font-size: 15px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-sans);
  color: var(--text-dark);
  background-color: var(--bg-page);
  line-height: 1.65;
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
  transition: all 0.2s ease;
}

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

ul, ol {
  list-style: none;
}

button {
  font-family: inherit;
  background: none;
  border: none;
  cursor: pointer;
}

/* --------------------------------------------------------------------------
   CSS PAGE TRANSITIONS (W3C View Transitions API + Universal Fallback)
   -------------------------------------------------------------------------- */

/* Native Cross-Document View Transitions (Chromium 126+, Modern Browsers) */
@view-transition {
  navigation: auto;
}

/* Custom View Transition Animations for Page Content */
::view-transition-old(root) {
  animation: 0.22s cubic-bezier(0.4, 0, 1, 1) both vtPageExit;
}

::view-transition-new(root) {
  animation: 0.28s cubic-bezier(0.16, 1, 0.3, 1) both vtPageEnter;
}

@keyframes vtPageExit {
  from {
    opacity: 1;
    transform: translateY(0);
  }
  to {
    opacity: 0;
    transform: translateY(-8px);
  }
}

@keyframes vtPageEnter {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Universal Progressive Enhancement Fallback for All Browsers */
main {
  animation: pageFadeIn 0.35s cubic-bezier(0.16, 1, 0.3, 1) both;
}

@keyframes pageFadeIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Smooth exit transition when navigating to an internal link */
body.page-is-leaving main {
  opacity: 0;
  transform: translateY(-8px);
  transition: opacity 0.18s cubic-bezier(0.4, 0, 1, 1), transform 0.18s cubic-bezier(0.4, 0, 1, 1);
}

/* Accessibility: Disable motion when user requests reduced motion */
@media (prefers-reduced-motion: reduce) {
  ::view-transition-group(*),
  ::view-transition-old(*),
  ::view-transition-new(*) {
    animation: none !important;
  }
  main,
  body.page-is-leaving main {
    animation: none !important;
    transition: none !important;
  }
}

.site-container {
  width: 100%;
  max-width: var(--site-max-w);
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}

/* --------------------------------------------------------------------------
   TYPOGRAPHY & SECTION UTILITIES
   -------------------------------------------------------------------------- */
.section-padded {
  padding: 4.5rem 0;
}

.section-padded-sm {
  padding: 3rem 0;
}

.section-title-wrapper {
  text-align: center;
  margin-bottom: 2.5rem;
}

.pre-heading,
.section-tag,
.theme-section-tag {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  color: var(--accent-gold);
  text-transform: uppercase;
  margin-bottom: 0.65rem;
}

.main-heading {
  font-family: var(--font-serif);
  font-size: 2.25rem;
  font-weight: 600;
  color: var(--primary-navy);
  line-height: 1.25;
  margin-bottom: 1rem;
}

.body-lead {
  font-size: 1.05rem;
  line-height: 1.7;
  color: var(--text-muted);
}

.body-desc {
  font-size: 0.95rem;
  line-height: 1.65;
  color: var(--text-muted);
}

.underlined-title {
  display: inline-block;
  position: relative;
  padding-bottom: 4px;
}

.underlined-title::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--accent-gold);
}

/* Buttons */
.theme-btn-primary,
.btn-theme-gold {
  background-color: var(--accent-gold);
  color: #ffffff !important;
  padding: 0.75rem 1.6rem;
  font-size: 0.88rem;
  font-weight: 600;
  border-radius: 4px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border: 1px solid var(--accent-gold);
  cursor: pointer;
  transition: all 0.2s ease;
}

.theme-btn-primary:hover,
.btn-theme-gold:hover {
  background-color: var(--accent-gold-dark);
  border-color: var(--accent-gold-dark);
}

.theme-btn-secondary,
.btn-theme-outline {
  background-color: transparent;
  color: var(--primary-navy);
  border: 1px solid #94a3b8;
  padding: 0.75rem 1.6rem;
  font-size: 0.88rem;
  font-weight: 600;
  border-radius: 4px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.theme-btn-secondary:hover,
.btn-theme-outline:hover {
  border-color: var(--primary-navy);
  color: var(--primary-navy);
}

/* --------------------------------------------------------------------------
   INSTITUTIONAL HEADER
   -------------------------------------------------------------------------- */
.theme-header {
  background-color: #ffffff;
  border-bottom: 1px solid #f1f5f9;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.03);
  view-transition-name: main-site-header;
}

.header-layout {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 78px;
}

.brand-box {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.brand-monogram {
  font-family: var(--font-serif);
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--primary-navy);
  line-height: 1;
}

.brand-meta {
  display: flex;
  flex-direction: column;
}

.meta-title {
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--primary-navy);
  line-height: 1.2;
}

.meta-sub {
  font-size: 0.62rem;
  color: var(--accent-gold);
  letter-spacing: 0.08em;
  font-weight: 600;
}

.center-nav {
  display: flex;
  align-items: center;
}

.nav-links-row {
  display: flex;
  align-items: center;
  gap: 1.4rem;
  list-style: none;
}

.theme-nav-item {
  font-size: 0.84rem;
  font-weight: 500;
  color: #334155;
  padding: 0.5rem 0;
  position: relative;
}

.theme-nav-item:hover {
  color: var(--primary-navy);
}

.theme-nav-item.active {
  color: var(--primary-navy);
  font-weight: 600;
}

.theme-nav-item.active::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 2px;
  background-color: var(--accent-gold);
}

.menu-hamburger {
  display: none;
  flex-direction: column;
  gap: 4px;
  padding: 6px;
}

.menu-hamburger span {
  width: 22px;
  height: 2px;
  background-color: #334155;
}

/* Mobile Drawer */
.theme-mobile-drawer {
  position: fixed;
  inset: 0;
  z-index: 200;
  background-color: #ffffff;
  display: flex;
  flex-direction: column;
  padding: 1.5rem;
  transform: translateX(100%);
  transition: transform 0.25s ease;
  overflow-y: auto;
}

.theme-mobile-drawer.open {
  transform: translateX(0);
}

.drawer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border-light);
  padding-bottom: 1rem;
  margin-bottom: 1rem;
}

.drawer-logo {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-navy);
}

.drawer-close {
  font-size: 1.8rem;
  color: #334155;
  cursor: pointer;
}

.drawer-nav {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.drawer-nav a {
  font-size: 1rem;
  font-weight: 500;
  color: #334155;
}

.drawer-nav a.active {
  color: var(--accent-gold);
  font-weight: 700;
}

/* --------------------------------------------------------------------------
   MASTER FOOTER
   -------------------------------------------------------------------------- */
.theme-footer {
  background-color: #ffffff;
  border-top: 1px solid var(--border-light);
  margin-top: 2rem;
  padding-top: 45px;
}

.footer-main-body {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 2rem;
  padding-bottom: 35px;
}

.footer-left-col {
  display: flex;
  flex-direction: column;
}

.footer-logo {
  font-family: var(--font-serif);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--primary-navy);
  letter-spacing: 0.06em;
}

.footer-name {
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--primary-navy);
  letter-spacing: 0.05em;
  line-height: 1.2;
}

.footer-tag {
  font-size: 0.65rem;
  color: var(--accent-gold);
  letter-spacing: 0.06em;
}

.footer-center-col {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.78rem;
  color: #475569;
}

.footer-links-row-top,
.footer-links-row-sub {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.footer-center-col a:hover {
  color: var(--primary-navy);
}

.footer-center-col .sep {
  color: #cbd5e1;
}

.footer-right-col {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 0.4rem;
}

.follow-label {
  font-size: 0.74rem;
  font-weight: 600;
  color: #64748b;
}

.social-icons-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  color: #334155;
}

.social-icons-row a:hover {
  color: var(--accent-gold);
}

/* Dark Bottom Strip */
.footer-dark-strip {
  background-color: var(--bg-dark-footer);
  color: #94a3b8;
  padding: 0.75rem 0;
  font-size: 0.72rem;
}

.dark-strip-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.scroll-up-btn {
  background-color: var(--accent-gold);
  color: #ffffff;
  border-radius: 3px;
  width: 24px;
  height: 24px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 0.85rem;
  cursor: pointer;
}

/* Responsive Header & Footer */
@media (max-width: 900px) {
  .center-nav {
    display: none;
  }
  .menu-hamburger {
    display: flex;
  }
  .footer-main-body {
    flex-direction: column;
    align-items: flex-start;
  }
  .footer-right-col {
    align-items: flex-start;
  }
}

@media (max-width: 600px) {
  .dark-strip-inner {
    flex-direction: column;
    gap: 0.5rem;
    align-items: flex-start;
  }
}