/* ตัวแปรสี */
:root {
  --primary-color: #1e3c72;
  --secondary-color: #2a5298;
  --reading-color: #3b5998;
  --math-color: #e91e63;
  --science-color: #4caf50;
  --dark-color: #343a40;
  --light-color: #f8f9fa;
}

/* พื้นฐาน */
body {
  font-family: 'Sarabun', sans-serif;
  background-color: var(--light-color);
  color: #333;
  line-height: 1.6;
}

/* Navbar */
.navbar-brand {
  font-weight: 700;
  font-size: 1.5rem;
}

.navbar-dark {
  background-color: var(--dark-color) !important;
}

/* Jumbotron */
.jumbotron {
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
  color: white;
  border-radius: 10px;
  padding: 2rem;
  margin-bottom: 2rem;
}

/* การ์ดหมวดหมู่ */
.category-card {
  transition: transform 0.3s, box-shadow 0.3s;
  margin-bottom: 20px;
  border: none;
  border-radius: 10px;
  overflow: hidden;
  box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.category-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 20px rgba(0,0,0,0.15);
}

.category-card img {
  height: 200px;
  object-fit: cover;
}

/* Badges */
.badge-reading {
  background-color: var(--reading-color);
}

.badge-math {
  background-color: var(--math-color);
}

.badge-science {
  background-color: var(--science-color);
}

/* Footer */
footer {
  background-color: var(--dark-color);
  color: white;
  padding: 30px 0;
  margin-top: 50px;
}

/* ปุ่ม */
.btn-primary {
  background-color: var(--primary-color);
  border-color: var(--primary-color);
}

.btn-primary:hover {
  background-color: var(--secondary-color);
  border-color: var(--secondary-color);
}

/* ตาราง */
.table th {
  background-color: var(--primary-color);
  color: white;
}

/* Responsive */
@media (max-width: 768px) {
  .jumbotron {
    padding: 1.5rem;
  }
  
  .category-card {
    margin-bottom: 15px;
  }
}