:root {
  --primary-color: #1E90FF;
  --secondary-color: #FFD700;
  --bg-light: #FFFFFF;
  --bg-gray: #F5F7FA;
  --accent-green: #32CD32;
  --accent-orange: #FFA500;
  --text-dark: #2D3748;
  --text-light: #FFFFFF;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.12);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.1);
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.1);
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 16px;
  --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}

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

body {
  font-family: 'Helvetica Neue', Arial, sans-serif;
  line-height: 1.6;
  color: var(--text-dark);
  background: linear-gradient(135deg, var(--bg-gray), var(--bg-light));
  padding: 0;
  margin: 0;
}

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

.header {
  background: linear-gradient(135deg, var(--primary-color), #0F52BA);
  color: var(--text-light);
  padding: 2rem 0;
  text-align: center;
  margin-bottom: 3rem;
  box-shadow: var(--shadow-md);
  position: relative;
  overflow: hidden;
}

.header::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, rgba(255,255,255,0) 70%);
  animation: pulse 15s infinite linear;
}

@keyframes pulse {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

.header h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  position: relative;
  z-index: 1;
  text-shadow: 0 2px 4px rgba(0,0,0,0.3);
}

.notice {
  background-color: rgba(255,255,255,0.2);
  padding: 1rem;
  border-radius: var(--radius-md);
  margin: 2rem auto;
  max-width: 800px;
  text-align: center;
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow-sm);
}

.article-container {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 2rem;
  margin-bottom: 3rem;
}

@media (max-width: 900px) {
  .article-container {
    grid-template-columns: 1fr;
  }
}

article {
  background-color: var(--bg-light);
  padding: 2rem;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
}

article h2 {
  color: var(--primary-color);
  margin-bottom: 1.5rem;
  font-size: 1.8rem;
  position: relative;
  padding-bottom: 0.5rem;
}

article h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 60px;
  height: 3px;
  background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
}

article h3 {
  color: var(--secondary-color);
  margin: 1.5rem 0 1rem;
  font-size: 1.4rem;
}

article p {
  margin-bottom: 1.2rem;
  font-size: 1.05rem;
}

pre {
  background: #282C34;
  color: #ABB2BF;
  padding: 1.5rem;
  border-radius: var(--radius-md);
  margin: 1.5rem 0;
  overflow-x: auto;
  box-shadow: var(--shadow-sm);
  font-family: 'Fira Code', monospace;
  font-size: 0.9rem;
  line-height: 1.5;
}

code {
  font-family: 'Fira Code', monospace;
  background: rgba(40, 44, 52, 0.1);
  padding: 0.2rem 0.4rem;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
}

.sidebar {
  position: sticky;
  top: 2rem;
  align-self: start;
}

.nav-card {
  background-color: var(--bg-light);
  padding: 1.5rem;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  margin-bottom: 2rem;
}

.nav-card h3 {
  color: var(--primary-color);
  margin-bottom: 1rem;
  font-size: 1.2rem;
}

.nav-links {
  list-style: none;
}

.nav-links li {
  margin-bottom: 0.8rem;
}

.nav-links a {
  color: var(--text-dark);
  text-decoration: none;
  display: block;
  padding: 0.5rem 0;
  transition: var(--transition);
  position: relative;
}

.nav-links a::before {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
  transition: var(--transition);
}

.nav-links a:hover {
  color: var(--primary-color);
}

.nav-links a:hover::before {
  width: 100%;
}

.image-gallery {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin-top: 2rem;
}

.gallery-item {
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.gallery-item:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}

.gallery-item img {
  width: 100%;
  height: auto;
  display: block;
}

.footer {
  background: linear-gradient(135deg, var(--primary-color), #0F52BA);
  color: var(--text-light);
  padding: 2rem 0;
  text-align: center;
  margin-top: 3rem;
}

.highlight {
  background: linear-gradient(120deg, rgba(30,144,255,0.3), rgba(30,144,255,0));
  padding: 0.2rem 0.4rem;
  border-radius: var(--radius-sm);
}

.tooltip {
  position: relative;
  display: inline-block;
  border-bottom: 1px dotted var(--primary-color);
  cursor: help;
}

.tooltip .tooltiptext {
  visibility: hidden;
  width: 200px;
  background-color: var(--text-dark);
  color: var(--text-light);
  text-align: center;
  border-radius: var(--radius-sm);
  padding: 0.5rem;
  position: absolute;
  z-index: 1;
  bottom: 125%;
  left: 50%;
  margin-left: -100px;
  opacity: 0;
  transition: opacity 0.3s;
}

.tooltip:hover .tooltiptext {
  visibility: visible;
  opacity: 1;
}

.collapsible {
  background-color: var(--bg-gray);
  color: var(--text-dark);
  cursor: pointer;
  padding: 1rem;
  width: 100%;
  border: none;
  text-align: left;
  outline: none;
  font-size: 1rem;
  margin: 0.5rem 0;
  border-radius: var(--radius-md);
  transition: var(--transition);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.collapsible::after {
  content: '+';
  font-size: 1.2rem;
  color: var(--primary-color);
}

.collapsible.active::after {
  content: '-';
}

.collapsible:hover {
  background-color: #E2E8F0;
}

.collapsible-content {
  padding: 0 1rem;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.2s ease-out;
  background-color: var(--bg-light);
  border-radius: 0 0 var(--radius-md) var(--radius-md);
  margin-bottom: 1rem;
}

@media (max-width: 768px) {
  .header h1 {
    font-size: 2rem;
  }
  
  article {
    padding: 1.5rem;
  }
  
  .image-gallery {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .header {
    padding: 1.5rem 0;
  }
  
  .header h1 {
    font-size: 1.8rem;
  }
  
  article {
    padding: 1rem;
  }
  
  article h2 {
    font-size: 1.5rem;
  }
  
  article h3 {
    font-size: 1.2rem;
  }
}