/* ============================================================
   MASTERS OF CLOUD - MODERN REDESIGN
   ============================================================ */

/* ============================================================
   RESET & BASE
   ============================================================ */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --white:           #f5f3ef;
  --off-white:       #fafaf8;
  --black:           #0a0a0a;
  --dark-bg:         #1a1a1a;
  --accent-primary:  #2563eb;
  --accent-secondary:#0ea5e9;
  --accent-warm:     #f59e0b;
  --text-primary:    #f5f3ef;
  --text-secondary:  rgba(245,243,239,0.7);
  --text-muted:      rgba(245,243,239,0.5);
  --overlay-dark:    rgba(10,10,10,0.55);
  --overlay-deep:    rgba(10,10,10,0.78);
  
  --font-serif:      'Cormorant Garamond', Georgia, serif;
  --font-sans:       'Inter', system-ui, -apple-system, sans-serif;
  
  --ease-out-expo:   cubic-bezier(0.16, 1, 0.3, 1);
  --ease-in-out:     cubic-bezier(0.76, 0, 0.24, 1);
  --ease-out-quad:   cubic-bezier(0.25, 0.46, 0.45, 0.94);
  
  --header-h:        72px;
  --transition-fast: 0.2s;
  --transition-base: 0.35s;
  --transition-slow: 0.6s;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  background: var(--black);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-weight: 300;
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
}

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

/* ============================================================
   NOISE TEXTURE (intro section only)
   ============================================================ */
.intro::before {
  content: '';
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)' opacity='1'/%3E%3C/svg%3E");
  opacity: 0.03;
  pointer-events: none;
  z-index: 100;
  animation: noiseShift 0.5s steps(1) infinite;
}

@keyframes noiseShift {
  0%   { transform: translate(0, 0); }
  20%  { transform: translate(-5%, -5%); }
  40%  { transform: translate(5%, -5%); }
  60%  { transform: translate(-5%, 5%); }
  80%  { transform: translate(5%, 5%); }
  100% { transform: translate(0, 0); }
}

/* ============================================================
   SITE HEADER
   ============================================================ */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 clamp(24px, 4vw, 60px);
  z-index: 500;
  background: transparent;
  transition: all var(--transition-base) var(--ease-out-expo);
}

.site-header.scrolled {
  background: rgba(10, 10, 10, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
}

.header-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  z-index: 10;
}

.brand-logo {
  display: flex;
  align-items: center;
  transition: transform var(--transition-base);
}

.brand-logo:hover {
  transform: scale(1.05);
}

.brand-logo img {
  height: 50px;
  width: auto;
}

.brand-tagline {
  font-family: var(--font-serif);
  font-size: 0.85rem;
  font-weight: 300;
  font-style: italic;
  color: var(--accent-secondary);
  letter-spacing: 0.05em;
}

.header-nav {
  display: flex;
  gap: clamp(20px, 3vw, 48px);
  align-items: center;
}

.nav-item {
  font-size: 0.75rem;
  font-weight: 400;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
  position: relative;
  transition: color var(--transition-fast);
}

.nav-item::after {
  content: '';
  position: absolute;
  bottom: -3px;
  left: 0;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--accent-secondary), var(--accent-primary));
  transition: width var(--transition-base) var(--ease-out-expo);
}

.nav-item:hover,
.nav-item.active {
  color: var(--text-primary);
}

.nav-item:hover::after,
.nav-item.active::after {
  width: 100%;
}

.header-menu-toggle {
  display: none;
  flex-direction: column;
  gap: 6px;
  cursor: pointer;
  padding: 8px;
  z-index: 10;
}

.header-menu-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 1px;
  transition: all var(--transition-base);
}

.header-menu-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translateY(10px);
}

.header-menu-toggle.active span:nth-child(2) {
  transform: rotate(-45deg) translateY(-10px);
}

/* ============================================================
   INTRO SECTION
   ============================================================ */
.intro {
  position: relative;
  height: 100vh;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  padding-top: var(--header-h);
}

.intro-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}

.slides {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
}

.slides > div {
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
  background-attachment: fixed;
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity 3s ease;
}

.slide-active {
  opacity: 1 !important;
  transition-delay: 0.6s;
}

.intro-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(10,10,10,0.65) 0%, rgba(10,10,10,0.45) 100%);
  z-index: 1;
}

.intro-content {
  position: relative;
  z-index: 2;
  text-align: center;
  max-width: 900px;
  padding: 2rem;
  animation: fadeInUp 0.8s var(--ease-out-expo) 0.2s both;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.intro-eyebrow {
  font-size: clamp(0.9rem, 2vw, 1.1rem);
  font-weight: 300;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent-secondary);
  margin-bottom: 1rem;
}

.intro-title {
  font-family: var(--font-serif);
  font-size: clamp(3rem, 10vw, 8rem);
  font-weight: 300;
  line-height: 1;
  letter-spacing: -0.02em;
  margin-bottom: 1.5rem;
  background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.intro-title .line {
  display: block;
}

.intro-tagline {
  font-size: clamp(1rem, 2vw, 1.3rem);
  font-weight: 300;
  color: var(--text-secondary);
  margin-bottom: 2.5rem;
  letter-spacing: 0.05em;
}

.intro-cta {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  padding: 16px 40px;
  font-size: 0.9rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  color: var(--white);
  border: none;
  border-radius: 2px;
  cursor: pointer;
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.intro-cta::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, var(--accent-secondary), var(--accent-primary));
  opacity: 0;
  transition: opacity var(--transition-base);
}

.intro-cta:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 30px rgba(37, 99, 235, 0.3);
}

.intro-cta:hover::before {
  opacity: 1;
}

.intro-cta svg {
  width: 20px;
  height: 20px;
  transition: transform var(--transition-base);
}

.intro-cta:hover svg {
  transform: translateY(3px);
}

.intro-scroll-hint {
  position: absolute;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%);
  font-size: 0.75rem;
  font-weight: 400;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-muted);
  animation: bounce 2s infinite;
  z-index: 2;
}

@keyframes bounce {
  0%, 100% {
    transform: translateX(-50%) translateY(0);
  }
  50% {
    transform: translateX(-50%) translateY(-10px);
  }
}

/* ============================================================
   STATISTICS SECTION
   ============================================================ */
.statistics {
  background: linear-gradient(135deg, var(--dark-bg) 0%, rgba(26,26,26,0.8) 100%);
  padding: 60px clamp(24px, 4vw, 60px);
  border-top: 1px solid rgba(245, 243, 239, 0.1);
  border-bottom: 1px solid rgba(245, 243, 239, 0.1);
}

.stats-container {
  max-width: 1400px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 40px;
  text-align: center;
}

.stat {
  animation: fadeInUp 0.8s var(--ease-out-expo) forwards;
  opacity: 0;
}

.stat:nth-child(1) { animation-delay: 0s; }
.stat:nth-child(2) { animation-delay: 0.1s; }
.stat:nth-child(3) { animation-delay: 0.2s; }
.stat:nth-child(4) { animation-delay: 0.3s; }

.stat-label {
  display: block;
  font-size: 0.75rem;
  font-weight: 400;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.statcounter {
  font-family: var(--font-serif);
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 300;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ============================================================
   COURSES SECTION
   ============================================================ */
.courses {
  background: linear-gradient(135deg, rgba(10,10,10,0.3) 0%, rgba(26,26,26,0.2) 100%);
  padding: 100px clamp(24px, 4vw, 60px);
  position: relative;
}

.courses::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 20% 50%, rgba(37,99,235,0.05) 0%, transparent 50%);
  pointer-events: none;
}

.courses-inner {
  max-width: 1400px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.section-header {
  text-align: center;
  margin-bottom: 80px;
}

.section-header h2 {
  font-family: var(--font-serif);
  font-size: clamp(2.5rem, 6vw, 4rem);
  font-weight: 300;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.section-header p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  letter-spacing: 0.03em;
}

.courses-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 32px;
}

.course-card {
  position: relative;
  height: 400px;
  border-radius: 12px;
  overflow: hidden;
  group: course-card;
  animation: fadeInUp 0.8s var(--ease-out-expo) forwards;
  opacity: 0;
}

.course-card:nth-child(1) { animation-delay: 0s; }
.course-card:nth-child(2) { animation-delay: 0.1s; }
.course-card:nth-child(3) { animation-delay: 0.2s; }
.course-card:nth-child(4) { animation-delay: 0.3s; }
.course-card:nth-child(5) { animation-delay: 0.4s; }
.course-card:nth-child(6) { animation-delay: 0.5s; }

.card-bg {
  position: absolute;
  inset: 0;
  background-size: cover;
  background-position: center;
  transition: transform var(--transition-base) var(--ease-out-expo);
}

.card-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(10,10,10,0.4) 0%, rgba(10,10,10,0.7) 100%);
  transition: background var(--transition-base);
  z-index: 1;
}

.card-content {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  padding: 32px;
  z-index: 2;
  transition: all var(--transition-base);
}

.card-title {
  font-family: var(--font-serif);
  font-size: 1.8rem;
  font-weight: 300;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.card-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin-bottom: 20px;
  line-height: 1.5;
  opacity: 0;
  transition: opacity var(--transition-base);
}

.card-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-secondary);
  position: relative;
  width: fit-content;
  opacity: 0;
  transition: opacity var(--transition-base);
}

.card-link span {
  transition: transform var(--transition-base);
}

.card-link:hover span {
  transform: translateX(4px);
}

.course-card:hover .card-bg {
  transform: scale(1.08);
}

.course-card:hover .card-overlay {
  background: linear-gradient(135deg, rgba(10,10,10,0.3) 0%, rgba(10,10,10,0.8) 100%);
}

.course-card:hover .card-desc,
.course-card:hover .card-link {
  opacity: 1;
}

/* ============================================================
   RESOURCES SECTION
   ============================================================ */
.resources {
  background: linear-gradient(135deg, rgba(10,10,10,0.5) 0%, var(--dark-bg) 100%);
  padding: 100px clamp(24px, 4vw, 60px);
  border-top: 1px solid rgba(245, 243, 239, 0.1);
  position: relative;
  overflow: hidden;
}

.resources::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 80% 50%, rgba(14,165,233,0.05) 0%, transparent 50%);
  pointer-events: none;
}

.resources-inner {
  max-width: 900px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.resource-list {
  list-style: none;
  margin-top: 60px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.resource-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  background: linear-gradient(135deg, rgba(245,243,239,0.05) 0%, rgba(245,243,239,0.02) 100%);
  border: 1px solid rgba(245, 243, 239, 0.1);
  border-radius: 8px;
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.resource-item::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: linear-gradient(180deg, var(--accent-primary), var(--accent-secondary));
  transform: scaleY(0);
  transform-origin: center;
  transition: transform var(--transition-base);
}

.resource-item:hover::before {
  transform: scaleY(1);
}

.resource-item span {
  font-size: 1rem;
  font-weight: 400;
  color: var(--text-primary);
  transition: color var(--transition-fast);
}

.resource-item svg {
  width: 20px;
  height: 20px;
  color: var(--accent-secondary);
  transition: transform var(--transition-base);
}

.resource-item:hover {
  background: linear-gradient(135deg, rgba(245,243,239,0.08) 0%, rgba(245,243,239,0.04) 100%);
  border-color: rgba(245, 243, 239, 0.15);
}

.resource-item:hover span {
  color: var(--accent-secondary);
}

.resource-item:hover svg {
  transform: translateX(4px);
}

/* ============================================================
   FOOTER SECTION
   ============================================================ */
.site-footer {
  background: var(--black);
  padding: 80px clamp(24px, 4vw, 60px) 40px;
  border-top: 1px solid rgba(245, 243, 239, 0.1);
  position: relative;
}

.footer-content {
  max-width: 800px;
  margin: 0 auto;
  text-align: center;
  margin-bottom: 60px;
}

.site-footer h2 {
  font-family: var(--font-serif);
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 300;
  letter-spacing: -0.01em;
  margin-bottom: 1rem;
}

.footer-text {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 40px;
  letter-spacing: 0.03em;
}

.social-links {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-bottom: 40px;
}

.social-links a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 2px solid rgba(245, 243, 239, 0.2);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.social-links a::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  opacity: 0;
  transition: opacity var(--transition-base);
  z-index: -1;
}

.social-links a svg {
  width: 24px;
  height: 24px;
  transition: color var(--transition-fast);
}

.social-links a:hover {
  border-color: transparent;
}

.social-links a:hover::before {
  opacity: 1;
}

.social-links a:hover svg {
  color: var(--white);
  transform: scale(1.1);
}

.footer-bottom {
  text-align: center;
  padding-top: 40px;
  border-top: 1px solid rgba(245, 243, 239, 0.1);
  font-size: 0.85rem;
  color: var(--text-muted);
  letter-spacing: 0.05em;
}

.return-to-top {
  position: fixed;
  bottom: 40px;
  right: 40px;
  width: 50px;
  height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px solid rgba(245, 243, 239, 0.2);
  border-radius: 50%;
  background: rgba(10, 10, 10, 0.7);
  backdrop-filter: blur(8px);
  cursor: pointer;
  transition: all var(--transition-base);
  opacity: 0;
  pointer-events: none;
  z-index: 400;
}

.return-to-top.visible {
  opacity: 1;
  pointer-events: all;
}

.return-to-top:hover {
  border-color: var(--accent-secondary);
  background: rgba(10, 10, 10, 0.9);
}

.return-to-top svg {
  width: 24px;
  height: 24px;
  color: var(--accent-secondary);
  transition: transform var(--transition-base);
}

.return-to-top:hover svg {
  transform: translateY(-4px);
}

/* ============================================================
   RESPONSIVE DESIGN
   ============================================================ */

@media screen and (max-width: 1024px) {
  :root {
    --header-h: 64px;
  }

  .courses-grid {
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
  }

  .intro-title {
    font-size: clamp(2.5rem, 8vw, 5rem);
  }

  .stat {
    padding: 20px 0;
  }
}

@media screen and (max-width: 768px) {
  :root {
    --header-h: 56px;
  }

  .header-nav {
    gap: 16px;
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    flex-direction: column;
    background: rgba(10, 10, 10, 0.95);
    backdrop-filter: blur(12px);
    padding: 24px;
    gap: 16px;
    max-height: calc(100vh - var(--header-h));
    overflow-y: auto;
    transform: translateX(-100%);
    transition: transform var(--transition-base);
    z-index: 400;
    display: none;
  }

  .header-nav.active {
    display: flex;
    transform: translateX(0);
  }

  .nav-item {
    font-size: 0.7rem;
    padding: 12px 0;
  }

  .brand-logo img {
    height: 40px;
  }

  .header-menu-toggle {
    display: flex;
  }

  .intro {
    height: 80vh;
  }

  .intro-title {
    font-size: clamp(1.8rem, 8vw, 3rem);
  }

  .intro-tagline {
    font-size: 0.95rem;
  }

  .courses-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .course-card {
    height: 300px;
  }

  .stats-container {
    gap: 24px;
  }

  .social-links {
    gap: 16px;
  }

  .social-links a {
    width: 40px;
    height: 40px;
  }

  .social-links a svg {
    width: 20px;
    height: 20px;
  }

  .return-to-top {
    bottom: 20px;
    right: 20px;
    width: 44px;
    height: 44px;
  }

  .return-to-top svg {
    width: 20px;
    height: 20px;
  }
}

@media screen and (max-width: 480px) {
  :root {
    --header-h: 52px;
  }

  .header-brand {
    gap: 8px;
  }

  .brand-logo img {
    height: 32px;
  }

  .brand-tagline {
    display: none;
  }

  .intro {
    height: 100vh;
    padding-top: var(--header-h);
  }

  .intro-title {
    font-size: clamp(1.5rem, 6vw, 2.5rem);
  }

  .intro-eyebrow {
    font-size: 0.8rem;
  }

  .intro-tagline {
    font-size: 0.9rem;
  }

  .intro-cta {
    padding: 12px 28px;
    font-size: 0.8rem;
  }

  .intro-cta svg {
    width: 16px;
    height: 16px;
  }

  .section-header h2 {
    font-size: clamp(1.5rem, 5vw, 2rem);
  }

  .course-card {
    height: 250px;
  }

  .card-content {
    padding: 20px;
  }

  .card-title {
    font-size: 1.3rem;
  }

  .card-desc {
    font-size: 0.85rem;
    margin-bottom: 12px;
  }

  .stats-container {
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
  }

  .statcounter {
    font-size: clamp(1.5rem, 4vw, 2.5rem);
  }

  .resource-item {
    padding: 16px 20px;
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .resource-item span {
    font-size: 0.9rem;
  }

  .resource-item svg {
    align-self: flex-end;
  }

  .social-links {
    gap: 12px;
  }

  .social-links a {
    width: 36px;
    height: 36px;
  }

  .social-links a svg {
    width: 18px;
    height: 18px;
  }

  .footer-bottom {
    font-size: 0.75rem;
  }

  .return-to-top {
    bottom: 16px;
    right: 16px;
    width: 40px;
    height: 40px;
  }

  .return-to-top svg {
    width: 18px;
    height: 18px;
  }

  .intro-scroll-hint {
    font-size: 0.65rem;
    bottom: 20px;
  }
}

/* ============================================================
   ANIMATIONS
   ============================================================ */
@keyframes slideInDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

/* Reduce motion preferences */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* ============================================================
   PRINT STYLES
   ============================================================ */
@media print {
  .site-header,
  .site-footer,
  .return-to-top,
  .intro-scroll-hint,
  .noise {
    display: none;
  }

  body {
    background: white;
    color: black;
  }

  a {
    color: #2563eb;
    text-decoration: underline;
  }

  .section-header h2,
  .intro-title {
    color: black !important;
    -webkit-text-fill-color: unset;
  }
}

/* ============================================================
   WEBP IMAGE SUPPORT
   ============================================================ */
@supports (background-image: url("data:image/webp;base64,")) {
  .slides > div,
  .card-bg {
    /* Browsers supporting WebP will use WebP if available */
  }
}

/* ============================================================
   DARK MODE / LIGHT MODE SUPPORT
   ============================================================ */
@media (prefers-color-scheme: light) {
  :root {
    --white:           #0a0a0a;
    --off-white:       #1a1a1a;
    --black:           #f5f3ef;
    --dark-bg:         #fafaf8;
    --text-primary:    #0a0a0a;
    --text-secondary:  rgba(10,10,10,0.7);
    --text-muted:      rgba(10,10,10,0.5);
  }

  body {
    background: var(--black);
  }

  .site-header.scrolled {
    background: rgba(245, 243, 239, 0.85);
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.1);
  }

  .intro-overlay {
    background: linear-gradient(135deg, rgba(245,243,239,0.65) 0%, rgba(245,243,239,0.45) 100%);
  }

  .card-overlay {
    background: linear-gradient(135deg, rgba(245,243,239,0.4) 0%, rgba(245,243,239,0.7) 100%);
  }
}

/* ============================================================
   HIGH CONTRAST MODE
   ============================================================ */
@media (prefers-contrast: more) {
  :root {
    --accent-primary:  #0047ab;
    --accent-secondary:#0070c0;
  }

  .intro-cta {
    border: 2px solid currentColor;
  }

  .social-links a {
    border-width: 2px;
  }

  .return-to-top {
    border-width: 2px;
  }
}

/* ============================================================
   OPTIMIZATION: Loading States
   ============================================================ */
.course-card[data-loading="true"] .card-bg {
  background-color: rgba(255, 255, 255, 0.05);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% {
    opacity: 0.5;
  }
  50% {
    opacity: 1;
  }
}