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

/* Body */
body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: #fafafa;
  color: #333;
  line-height: 1.6;
}

/* Header */
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 40px;
  background-color: #7b9e3a;
}

header .logo {
  color: #fff;
  font-size: 1.8em;
  font-weight: bold;
}

nav ul {
  list-style: none;
  display: flex;
  gap: 25px;
}

nav ul li a {
  color: #ecf0f1;
  text-decoration: none;
  font-weight: 500;
  font-size: 1em;
  transition: color 0.3s;
}

nav ul li a:hover {
  color: #3498db;
}

/* Slider */
.slider-container {
  position: relative;
  width: 100%;
  max-width: 1000px;
  margin: 40px auto;
  overflow: hidden;
  border-radius: 10px;
}

.slider {
  position: relative;
  width: 100%;
  height: 400px;
}

.slide {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  transition: opacity 1s ease-in-out;
  object-fit: cover;
}

.slide.active {
  opacity: 1;
}

/* Sections */
section {
  padding: 50px 20px;
  background-color: #fff;
  margin-bottom: 20px;
}

h2 {
  text-align: center;
  margin-bottom: 30px;
  color: #2c3e50;
}

/* Book Grid */
.book-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 20px;
}

.book-card {
  width: 200px;
  background: #f4f4f4;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 4px 8px rgba(0,0,0,0.1);
  display: flex;
  flex-direction: column;
  align-items: center;
}

.book-card img {
  width: 100%;
  height: 250px;
  object-fit: cover;
}

.book-info {
  padding: 10px;
  text-align: center;
}

h3 {
  font-size: 1.1em;
  margin-bottom: 5px;
}

/* Thể loại sách */
.category-tags {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 15px;
}

.category-tags a {
  padding: 12px 25px;
  background-color: #2980b9;
  color: #fff;
  border-radius: 25px;
  text-decoration: none;
  font-size: 1em;
  transition: background-color 0.3s;
}

.category-tags a:hover {
  background-color: #3498db;
}

/* Video section */
.video-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 50px 20px;
  background-color: #f0f0f0;
}

iframe {
  width: 80%;
  height: 450px;
  border: none;
}

/* Footer */
footer {
  padding: 20px;
  background-color: #2c3e50;
  color: #ecf0f1;
  text-align: center;
  margin-top: 40px;
}