/* 1. Global design tokens (Variables) */
:root {
  --primary-color: #3498db;
  --secondary-color: #2ecc71;
  --text-dark: #2c3e50;
  --font-main: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  --border-radius: 8px;
}

/* 2. Base Element Resets */
body {
  font-family: var(--font-main);
  color: var(--text-dark);
  line-height: 1.6;
  padding: 20px;
}

/* 3. Reusable Component Classes */
.card {
  border: 1px solid #e0e0e0;
  border-radius: var(--border-radius);
  padding: 20px;
  margin-bottom: 15px;
  box-shadow: 3px 3px 10px rgba(0, 0, 0, 0.3);
}

.btn {
  display: inline-block;
  padding: 10px 20px;
  font-size: 1rem;
  font-weight: bold;
  text-align: center;
  text-decoration: none;
  border-radius: var(--border-radius);
  border: none;
  cursor: pointer;
  transition: opacity 0.2s ease;
}

.btn:hover {
  opacity: 0.9;
}

/* 4. Reusable Modifier Classes */
.btn-primary {
  background-color: var(--primary-color);
  color: white;
}

.btn-secondary {
  background-color: var(--secondary-color);
  color: white;
}