:root {
  --primary: #2e7d32;
  --primary-hover: #388e3c;
  --primary-light: #4caf50;
  --background: #0f1112;
  --background-panel: #181a1b;
  --background-elevated: #212425;
  --text-primary: #f1f3f5;
  --text-secondary: #b0b8c0;
  --text-tertiary: #8a9299;
  --border: rgba(255,255,255,0.08);
  --success: #4caf50;
  --radius: 12px;
  --shadow: 0 4px 20px rgba(0,0,0,0.3);
}

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

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background: var(--background);
  color: var(--text-primary);
  line-height: 1.6;
}

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

h1, h2, h3 {
  font-weight: 600;
  line-height: 1.2;
}

.section {
  padding: 60px 0;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 28px;
  background: var(--primary);
  color: white;
  text-decoration: none;
  border-radius: var(--radius);
  font-weight: 500;
  transition: all 0.2s ease;
  border: none;
  cursor: pointer;
  font-size: 15px;
}

.btn:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
}

.card {
  background: var(--background-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  transition: all 0.2s ease;
}

.card:hover {
  border-color: var(--primary);
  transform: translateY(-4px);
}

/* Header */
header {
  padding: 18px 0;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--background);
  z-index: 100;
}

nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 15px;
}

.logo {
  font-size: 24px;
  font-weight: 700;
  color: var(--primary);
}

/* Hero */
.hero {
  padding: 100px 0 80px;
  text-align: center;
}

.hero h1 {
  font-size: 42px;
  margin-bottom: 20px;
  line-height: 1.15;
}

.hero p {
  font-size: 18px;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto 32px;
}

/* Advantages */
.advantages {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
  margin-top: 40px;
}

/* Calculator */
.calculator {
  max-width: 560px;
  margin: 40px auto 0;
}

.calculator .card {
  padding: 28px;
}

.calculator label {
  display: block;
  margin-bottom: 6px;
  font-weight: 500;
  font-size: 14px;
}

.calculator input,
.calculator select {
  width: 100%;
  padding: 12px 16px;
  background: var(--background-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-primary);
  font-size: 16px;
  margin-bottom: 18px;
}

.result {
  margin-top: 24px;
  padding: 20px;
  background: var(--background-elevated);
  border-radius: var(--radius);
  border: 1px solid var(--primary);
  text-align: center;
}

.result .price {
  font-size: 28px;
  font-weight: 700;
  color: var(--primary-light);
}

/* Steps */
.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 18px;
  margin-top: 36px;
}

.steps > div {
  background: var(--background-panel);
  padding: 22px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

/* Responsive */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 30px;
  }
  
  .hero p {
    font-size: 16px;
  }
  
  .section {
    padding: 50px 0;
  }
  
  .advantages {
    grid-template-columns: 1fr;
  }
  
  .calculator .card {
    padding: 22px;
  }
}