/* Reset and Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  line-height: 1.6;
  color: #333;
  background-color: #f8f9fa;
}

/* Navigation */
header {
  background: linear-gradient(135deg, #1a365d 0%, #2c5282 100%);
  padding: 1rem 2rem;
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

nav {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-brand {
  font-size: 1.5rem;
  font-weight: 700;
  color: #fff;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 2rem;
}

.nav-links a {
  color: #e2e8f0;
  text-decoration: none;
  font-weight: 500;
  transition: color 0.3s ease;
}

.nav-links a:hover {
  color: #fff;
}

/* Hero Section */
.hero {
  background: linear-gradient(rgba(44, 82, 130, 0.85), rgba(26, 54, 93, 0.85)),
  url('images/metro.jpg');
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  color: #fff;
  padding: 5rem 2rem;
  text-align: center;
}

.hero h1 {
  font-size: 3rem;
  margin-bottom: 1rem;
  font-weight: 700;
}


.hero .subtitle {
  font-size: 1.25rem;
  opacity: 0.9;
  max-width: 600px;
  margin: 0 auto;
  color: aliceblue;
}

/* Main Content Container */
main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

section {
  padding: 4rem 0;
  border-bottom: 1px solid #e2e8f0;
}

section:last-of-type {
  border-bottom: none;
}

h2 {
  font-size: 2rem;
  color: #1a365d;
  margin-bottom: 1.5rem;
  text-align: center;
}

h3 {
  font-size: 1.5rem;
  color: #2c5282;
  margin-bottom: 1rem;
}

p {
  margin-bottom: 1rem;
  color: #4a5568;
}

/* Overview Section */
.overview p {
  text-align: center;
  max-width: 800px;
  margin: 0 auto 1rem;
  font-size: 1.1rem;
}

/* Methodology Section - Flip Cards */
.methodology-steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.flip-card {
  background-color: transparent;
  perspective: 1000px;
  height: 280px;
}

.flip-card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  text-align: center;
  transition: transform 0.8s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  transform-style: preserve-3d;
}

.flip-card:hover .flip-card-inner {
  transform: rotateY(180deg);
}

.flip-card-front,
.flip-card-back {
  position: absolute;
  width: 100%;
  height: 100%;
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
  border-radius: 12px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  padding: 2rem 1.5rem;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.flip-card-front {
  background: linear-gradient(135deg, #4299e1 0%, #2b6cb0 100%);
  color: #fff;
}

.flip-card-back {
  background: #fff;
  color: #333;
  transform: rotateY(180deg);
  border-left: 4px solid #4299e1;
}

.step-number {
  font-size: 3rem;
  font-weight: 700;
  color: rgba(255, 255, 255, 0.3);
  position: absolute;
  top: 1rem;
  right: 1.5rem;
}

.flip-card-front h3 {
  font-size: 1.4rem;
  color: #fff;
  margin-bottom: 0.5rem;
}

.flip-card-front p {
  color: rgba(255, 255, 255, 0.9);
  font-size: 0.9rem;
}

.flip-hint {
  font-size: 0.75rem !important;
  opacity: 0.7;
  margin-top: 1rem;
  font-style: italic;
}

.flip-card-back h3 {
  font-size: 1.2rem;
  color: #1a365d ;
  margin-bottom: 1rem;
}

.flip-card-back p {
  font-size: 0.9rem;
  line-height: 1.6;
  color: #4a5568;
}

/* Research Questions */
.questions-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.question-card {
  background: #fff;
  padding: 2rem;
  border-radius: 12px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  border-left: 4px solid #4299e1;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.question-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 15px rgba(0, 0, 0, 0.15);
}

.question-card h3 {
  font-size: 1.25rem;
  margin-bottom: 0.75rem;
}

/* Findings Section */
.finding {
  background: #fff;
  padding: 2rem;
  border-radius: 12px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  margin-bottom: 2rem;
}

.finding:last-child {
  margin-bottom: 0;
}

.chart-container {
  background: #fff;
  border: 1px solid #e2e8f0;
  border-radius: 8px;
  padding: 1rem;
  margin: 1.5rem 0;
  text-align: center;
}

.chart-container img {
  max-width: 100%;
  height: auto;
  border-radius: 4px;
}

.caption {
  text-align: center;
  font-style: italic;
  color: #718096;
  font-size: 0.9rem;
  margin-top: 1rem;
}

/* Map Section */
.map-section {
  background: #fff;
  border-radius: 12px;
  padding: 2rem;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  margin: 2rem 0;
}

.map-container {
  width: 100%;
  height: 600px;
  border: 1px solid #e2e8f0;
  border-radius: 8px;
  overflow: hidden;
}

.map-container iframe {
  width: 100%;
  height: 100%;
  border: none;
}

/* Data Summary Section */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.stat-card {
  background: linear-gradient(135deg, #4299e1 0%, #2b6cb0 100%);
  color: #fff;
  padding: 2rem 1.5rem;
  border-radius: 12px;
  text-align: center;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s ease;
}

.stat-card:hover {
  transform: translateY(-5px);
}

.stat-value {
  display: block;
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.stat-label {
  display: block;
  font-size: 0.9rem;
  opacity: 0.9;
}

/* Footer */
footer {
  background: #1a365d;
  color: #fff;
  text-align: center;
  padding: 2rem;
  margin-top: 2rem;
}

footer p {
  color: #cbd5e0;
  margin: 0.5rem 0;
}

/* Responsive Design */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 2rem;
  }

  .hero .subtitle {
    font-size: 1rem;
  }

  .nav-links {
    gap: 1rem;
    font-size: 0.9rem;
  }

  .questions-grid {
    grid-template-columns: 1fr;
  }

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

  .map-container {
    height: 400px;
  }

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

@media (max-width: 480px) {
  .stats-grid {
    grid-template-columns: 1fr;
  }

  section {
    padding: 2rem 0;
  }
}

/* Loading animation for images */
.chart-container img,
.map-container iframe {
  animation: fadeIn 0.5s ease-in;
}

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