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

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #7ef7c5 0%, #62c96f 100%);
  color: #333;
  line-height: 1.6;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 20px;
}

.header {
  text-align: center;
  padding: 60px 20px;
  background: white;
  border-radius: 20px;
  margin-bottom: 30px;
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.1);
}

.header h1 {
  font-size: 3em;
  color: #667eea;
  margin-bottom: 10px;
}

.header .subtitle {
  font-size: 1.3em;
  color: #666;
}

.section {
  background: white;
  border-radius: 20px;
  padding: 40px;
  margin-bottom: 30px;
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.1);
  animation: fadeIn 0.6s ease-in;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.section-title {
  font-size: 2.2em;
  color: #667eea;
  margin-bottom: 25px;
  padding-bottom: 15px;
  border-bottom: 4px solid #667eea;
}

.section-subtitle {
  font-size: 1.5em;
  color: #764ba2;
  margin: 25px 0 15px 0;
  display: flex;
  align-items: center;
}

.icon {
  font-size: 1.3em;
  margin-right: 10px;
}

.three-books {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 25px;
  margin: 30px 0;
}

.book-card {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 30px;
  border-radius: 15px;
  text-align: center;
  transition: transform 0.3s;
}

.book-card:hover {
  transform: translateY(-10px);
}

.book-card h3 {
  font-size: 1.6em;
  margin-bottom: 15px;
}

.book-card p {
  font-size: 1.1em;
  opacity: 0.9;
}

.formula-box {
  background: #f8f9ff;
  border-left: 5px solid #667eea;
  padding: 25px;
  margin: 20px 0;
  border-radius: 10px;
  font-size: 1.2em;
}

.formula-box strong {
  color: #667eea;
  font-size: 1.3em;
}

.highlight-box {
  background: linear-gradient(135deg, #ffeaa7 0%, #fdcb6e 100%);
  padding: 25px;
  border-radius: 15px;
  margin: 20px 0;
  border-left: 5px solid #f39c12;
}

.highlight-box strong {
  color: #d35400;
}

.comparison-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin: 25px 0;
}

.comparison-card {
  padding: 25px;
  border-radius: 15px;
  border: 3px solid #ddd;
}

.comparison-card.good {
  background: #d4edda;
  border-color: #28a745;
}

.comparison-card.bad {
  background: #f8d7da;
  border-color: #dc3545;
}

.comparison-card h4 {
  margin-bottom: 15px;
  font-size: 1.4em;
}

.stat-box {
  display: inline-block;
  background: #667eea;
  color: white;
  padding: 15px 30px;
  border-radius: 50px;
  margin: 10px 10px 10px 0;
  font-weight: bold;
  font-size: 1.1em;
}

.timeline {
  position: relative;
  padding-left: 40px;
  margin: 30px 0;
}

.timeline::before {
  content: "";
  position: absolute;
  left: 10px;
  top: 0;
  bottom: 0;
  width: 3px;
  background: #667eea;
}

.timeline-item {
  position: relative;
  margin-bottom: 30px;
  padding: 20px;
  background: #f8f9ff;
  border-radius: 10px;
}

.timeline-item::before {
  content: "●";
  position: absolute;
  left: -37px;
  top: 20px;
  color: #667eea;
  font-size: 1.5em;
}

.timeline-item h4 {
  color: #667eea;
  margin-bottom: 10px;
  font-size: 1.3em;
}

.example-box {
  background: #e8f5e9;
  border: 2px solid #4caf50;
  padding: 25px;
  border-radius: 15px;
  margin: 20px 0;
}

.example-box h4 {
  color: #2e7d32;
  margin-bottom: 15px;
  font-size: 1.4em;
}

.calculation {
  background: white;
  padding: 20px;
  border-radius: 10px;
  margin: 15px 0;
  font-family: "Courier New", monospace;
  font-size: 1.05em;
}

.calculation div {
  padding: 5px 0;
}

.calculation .total {
  border-top: 2px solid #333;
  margin-top: 10px;
  padding-top: 10px;
  font-weight: bold;
  font-size: 1.2em;
  color: #667eea;
}

ul.checklist {
  list-style: none;
  padding: 0;
}

ul.checklist li {
  padding: 12px 0;
  padding-left: 35px;
  position: relative;
  font-size: 1.1em;
}

ul.checklist li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: #4caf50;
  font-weight: bold;
  font-size: 1.4em;
}

.strategy-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
  margin: 25px 0;
}

.strategy-card {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 25px;
  border-radius: 15px;
  text-align: center;
}

.strategy-card h4 {
  font-size: 1.3em;
  margin-bottom: 15px;
}

.vs-box {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 20px;
  align-items: center;
  margin: 25px 0;
}

.vs-item {
  padding: 25px;
  border-radius: 15px;
  text-align: center;
}

.vs-item.free {
  background: #e3f2fd;
  border: 3px solid #2196f3;
}

.vs-item.discount {
  background: #fff3e0;
  border: 3px solid #ff9800;
}

.vs-divider {
  font-size: 2em;
  font-weight: bold;
  color: #667eea;
}

@media (max-width: 768px) {
  .header h1 {
    font-size: 2em;
  }

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

  .vs-box {
    grid-template-columns: 1fr;
  }

  .vs-divider {
    transform: rotate(90deg);
  }
}