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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  line-height: 1.6;
  color: #1f2937;
}

.container {
  min-height: 100vh;
  background: linear-gradient(135deg, #4ade80, #22c55e);
}

/* Header */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.5rem;
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
}

.logo {
  font-size: 1.5rem;
  font-weight: bold;
  color: white;
}

.nav {
  display: flex;
  gap: 2rem;
}

.nav-link {
  color: white;
  text-decoration: none;
  font-weight: 500;
  transition: all 0.3s;
  padding: 0.5rem 1rem;
  border-radius: 0.5rem;
}

.nav-link:hover,
.nav-link.active {
  background: rgba(255, 255, 255, 0.2);
  transform: translateY(-2px);
}

/* Hero Section */
.hero-section {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  padding: 4rem 2rem;
  align-items: center;
  min-height: 80vh;
}

.hero-content {
  color: white;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: rgba(255, 255, 255, 0.2);
  padding: 0.5rem 1rem;
  border-radius: 2rem;
  font-size: 0.875rem;
  margin-bottom: 2rem;
  backdrop-filter: blur(10px);
}

.hero-title {
  font-size: 3.5rem;
  font-weight: bold;
  line-height: 1.1;
  margin-bottom: 1.5rem;
}

.highlight {
  background: linear-gradient(45deg, #fbbf24, #f59e0b);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.25rem;
  opacity: 0.9;
  margin-bottom: 3rem;
  line-height: 1.6;
}

.hero-stats {
  display: flex;
  gap: 3rem;
}

.stat-item {
  text-align: center;
}

.stat-number {
  font-size: 2.5rem;
  font-weight: bold;
  margin-bottom: 0.5rem;
}

.stat-label {
  font-size: 0.875rem;
  opacity: 0.8;
}

.hero-visual {
  position: relative;
  height: 400px;
}

.floating-card {
  position: absolute;
  background: white;
  padding: 1.5rem;
  border-radius: 1rem;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  animation: float 6s ease-in-out infinite;
}

.floating-card i {
  font-size: 2rem;
  color: #22c55e;
}

.floating-card span {
  font-weight: 600;
  color: #1f2937;
}

.card-1 {
  top: 20%;
  left: 10%;
  animation-delay: 0s;
}

.card-2 {
  top: 10%;
  right: 20%;
  animation-delay: 1.5s;
}

.card-3 {
  bottom: 30%;
  left: 20%;
  animation-delay: 3s;
}

.card-4 {
  bottom: 10%;
  right: 10%;
  animation-delay: 4.5s;
}

@keyframes float {
  0%,
  100% {
    transform: translateY(0px);
  }
  50% {
    transform: translateY(-20px);
  }
}

/* Sections */
.papers-overview,
.answer-structure,
.mark-scheme {
  background: white;
  padding: 5rem 2rem;
}

.cta-section {
  background: linear-gradient(135deg, #1f2937, #374151);
  padding: 5rem 2rem;
  text-align: center;
}

.section-header {
  text-align: center;
  margin-bottom: 4rem;
}

.section-title {
  font-size: 2.5rem;
  font-weight: bold;
  margin-bottom: 1rem;
  color: #1f2937;
}

.section-subtitle {
  font-size: 1.125rem;
  color: #6b7280;
  max-width: 600px;
  margin: 0 auto;
}

/* Papers Grid */
.papers-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  max-width: 1200px;
  margin: 0 auto;
}

.paper-card {
  background: white;
  border-radius: 1.5rem;
  padding: 2rem;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
  transition: all 0.3s;
  border: 2px solid transparent;
}

.paper-card:hover {
  transform: translateY(-10px);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.15);
  border-color: #22c55e;
}

.paper-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.paper-icon {
  width: 3rem;
  height: 3rem;
  background: linear-gradient(135deg, #22c55e, #16a34a);
  border-radius: 0.75rem;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.25rem;
}

.paper-title {
  font-size: 1.25rem;
  font-weight: bold;
  margin-bottom: 0.25rem;
}

.paper-duration {
  font-size: 0.875rem;
  color: #6b7280;
}

.paper-description {
  margin-bottom: 1.5rem;
}

.paper-features {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-bottom: 2rem;
}

.feature {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: #6b7280;
}

.feature i {
  color: #22c55e;
}

.explore-btn {
  width: 100%;
  background: linear-gradient(135deg, #22c55e, #16a34a);
  color: white;
  border: none;
  padding: 0.75rem 1.5rem;
  border-radius: 0.75rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

.explore-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 20px rgba(34, 197, 94, 0.3);
}

/* Tabs */
.structure-tabs {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-bottom: 3rem;
}

.tab-btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 1rem 2rem;
  background: #f3f4f6;
  border: none;
  border-radius: 0.75rem;
  cursor: pointer;
  transition: all 0.3s;
  font-weight: 500;
}

.tab-btn.active {
  background: #22c55e;
  color: white;
}

.tab-btn:hover:not(.active) {
  background: #e5e7eb;
}

.tab-content {
  max-width: 1200px;
  margin: 0 auto;
}

.tab-panel {
  display: none;
}

.tab-panel.active {
  display: block;
}

/* Structure Steps */
.structure-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
}

.structure-step {
  background: #f8fafc;
  border-radius: 1rem;
  padding: 2rem;
  position: relative;
  border-left: 4px solid #22c55e;
}

.step-number {
  position: absolute;
  top: -1rem;
  left: 1.5rem;
  width: 2rem;
  height: 2rem;
  background: #22c55e;
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
}

.step-title {
  font-size: 1.125rem;
  font-weight: bold;
  margin-bottom: 0.5rem;
  margin-top: 1rem;
}

.step-description {
  color: #6b7280;
  margin-bottom: 1rem;
}

.step-tips {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.tip {
  font-size: 0.875rem;
  color: #22c55e;
}

/* Data Response Guide */
.data-response-guide {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.guide-section {
  background: #f8fafc;
  border-radius: 1rem;
  padding: 2rem;
  border-left: 4px solid #3b82f6;
}

.guide-title {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.25rem;
  font-weight: bold;
  margin-bottom: 1rem;
  color: #1f2937;
}

.guide-title i {
  color: #3b82f6;
}

.guide-content p {
  margin-bottom: 1rem;
  color: #6b7280;
}

.guide-list {
  list-style: none;
  padding-left: 0;
}

.guide-list li {
  padding: 0.5rem 0;
  padding-left: 1.5rem;
  position: relative;
  color: #374151;
}

.guide-list li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: #3b82f6;
  font-weight: bold;
}

/* MCQ Strategy */
.strategy-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}

.strategy-card {
  background: #f8fafc;
  border-radius: 1rem;
  padding: 2rem;
  text-align: center;
  border: 2px solid #e5e7eb;
  transition: all 0.3s;
}

.strategy-card:hover {
  border-color: #f59e0b;
  transform: translateY(-5px);
}

.strategy-icon {
  width: 4rem;
  height: 4rem;
  background: linear-gradient(135deg, #f59e0b, #d97706);
  border-radius: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1.5rem;
  color: white;
  font-size: 1.5rem;
}

.strategy-title {
  font-size: 1.25rem;
  font-weight: bold;
  margin-bottom: 1rem;
}

.strategy-description {
  color: #6b7280;
  margin-bottom: 1.5rem;
}

.strategy-tips {
  text-align: left;
}

.strategy-tips .tip {
  padding: 0.25rem 0;
  font-size: 0.875rem;
  color: #374151;
}

/* Mark Scheme Insights */
.insights-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  max-width: 1000px;
  margin: 0 auto;
}

.insight-card {
  background: white;
  border-radius: 1rem;
  padding: 2rem;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
  transition: all 0.3s;
}

.insight-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.15);
}

.insight-card.knowledge {
  border-top: 4px solid #3b82f6;
}

.insight-card.application {
  border-top: 4px solid #22c55e;
}

.insight-card.analysis {
  border-top: 4px solid #f59e0b;
}

.insight-card.evaluation {
  border-top: 4px solid #ef4444;
}

.insight-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.5rem;
}

.insight-icon {
  width: 3rem;
  height: 3rem;
  border-radius: 0.75rem;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.25rem;
}

.knowledge .insight-icon {
  background: #3b82f6;
}

.application .insight-icon {
  background: #22c55e;
}

.analysis .insight-icon {
  background: #f59e0b;
}

.evaluation .insight-icon {
  background: #ef4444;
}

.insight-title {
  font-size: 1.125rem;
  font-weight: bold;
}

.insight-percentage {
  font-size: 1.5rem;
  font-weight: bold;
  color: #6b7280;
}

.insight-description {
  color: #6b7280;
  margin-bottom: 1.5rem;
}

.insight-examples {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.example {
  font-size: 0.875rem;
  color: #22c55e;
}

/* CTA Section */
.cta-content {
  max-width: 600px;
  margin: 0 auto;
  color: white;
}

.cta-title {
  font-size: 2.5rem;
  font-weight: bold;
  margin-bottom: 1rem;
}

.cta-subtitle {
  font-size: 1.25rem;
  opacity: 0.9;
  margin-bottom: 2rem;
}

.cta-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  background: linear-gradient(135deg, #22c55e, #16a34a);
  color: white;
  text-decoration: none;
  padding: 1rem 2rem;
  border-radius: 0.75rem;
  font-weight: 600;
  transition: all 0.3s;
}

.cta-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 20px rgba(34, 197, 94, 0.3);
}

/* Footer */
.footer {
  background: #1f2937;
  color: white;
  padding: 3rem 2rem 1rem;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  max-width: 1200px;
  margin: 0 auto;
}

.footer-title {
  font-size: 1.125rem;
  font-weight: bold;
  margin-bottom: 1rem;
}

.footer-description {
  color: #9ca3af;
  line-height: 1.6;
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-links a {
  color: #9ca3af;
  text-decoration: none;
  transition: color 0.3s;
}

.footer-links a:hover {
  color: #22c55e;
}

.footer-bottom {
  border-top: 1px solid #374151;
  margin-top: 2rem;
  padding-top: 1rem;
  text-align: center;
  color: #9ca3af;
}

/* Responsive Design */
@media (max-width: 768px) {
  .hero-section {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .hero-title {
    font-size: 2.5rem;
  }

  .hero-stats {
    justify-content: center;
  }

  .structure-tabs {
    flex-direction: column;
    align-items: center;
  }

  .tab-btn {
    width: 100%;
    max-width: 300px;
  }
}