:root {
  --primary-color: #0047BB;
  --text-color: #333;
  --light-bg: #f5f7fa;
  --border-color: #e2e8f0;
  --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
}

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

body {
  font-family: Arial, sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background-color: #fff;
}

.container {
  max-width: 800px;
  margin: 30px auto;
  padding: 20px;
}

header {
  text-align: center;
  margin-bottom: 40px;
}

h1 {
  color: var(--primary-color);
  margin-bottom: 10px;
  font-size: 32px;
}

h2 {
  color: var(--primary-color);
  margin: 25px 0 15px;
  font-size: 24px;
}

h3 {
  font-size: 18px;
  margin: 20px 0 10px;
  color: var(--primary-color);
}

p {
  margin-bottom: 15px;
}

/* Tabs */
.tabs {
  display: flex;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 20px;
}

.tab {
  padding: 12px 20px;
  cursor: pointer;
  background: none;
  border: none;
  font-size: 16px;
  font-weight: 500;
  color: #666;
  position: relative;
  transition: color 0.3s;
}

.tab.active {
  color: var(--primary-color);
}

.tab.active::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--primary-color);
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
  animation: fadeIn 0.5s;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* Card */
.card {
  border: 1px solid var(--border-color);
  border-radius: 8px;
  margin-bottom: 20px;
  background-color: white;
  box-shadow: var(--card-shadow);
  overflow: hidden;
}

.card-header {
  padding: 20px 20px 10px;
}

.card-title {
  font-size: 22px;
  color: var(--primary-color);
  margin-bottom: 5px;
}

.card-description {
  color: #666;
  font-size: 14px;
}

.card-content {
  padding: 0 20px 20px;
}

/* Accordion */
.accordion {
  margin: 15px 0;
  border: 1px solid var(--border-color);
  border-radius: 4px;
}

.accordion-header {
  padding: 15px;
  background-color: var(--light-bg);
  cursor: pointer;
  font-weight: 500;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
}

.accordion-header::after {
  content: '+';
  font-size: 20px;
  transition: transform 0.3s;
}

.accordion.open .accordion-header::after {
  content: '−';
}

.accordion-content {
  padding: 0;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease-out, padding 0.3s ease;
}

.accordion.open .accordion-content {
  padding: 15px;
  max-height: 500px;
}

/* Grid */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 15px;
  margin: 20px 0;
}

.grid-item {
  background-color: var(--light-bg);
  padding: 15px;
  border-radius: 8px;
}

.highlight-box {
  background-color: #e6f0ff;
  border-radius: 8px;
  padding: 20px;
  margin: 20px 0;
}

/* Lists */
ul {
  padding-left: 20px;
  margin: 10px 0;
}

li {
  margin-bottom: 5px;
}

/* Footer */
footer {
  margin-top: 40px;
  padding-top: 20px;
  border-top: 1px solid var(--border-color);
  text-align: center;
  color: #666;
  font-size: 14px;
}

footer a {
  color: var(--primary-color);
  text-decoration: none;
  margin: 0 10px;
}

footer a:hover {
  text-decoration: underline;
}

/* Responsive */
@media (max-width: 768px) {
  .container {
    padding: 15px;
  }
  
  .grid {
    grid-template-columns: 1fr;
  }
  
  .tabs {
    flex-direction: column;
    border-bottom: none;
  }
  
  .tab {
    text-align: center;
    padding: 10px;
    border-bottom: 1px solid var(--border-color);
  }
  
  .tab.active::after {
    display: none;
  }
  
  .tab.active {
    background-color: var(--light-bg);
  }
}