.subtopic-container {
  max-width: 1000px;
  margin: 0 auto;
  padding: var(--space-8) var(--space-4);
}

.subtopic-header {
  margin-bottom: var(--space-8);
}

.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  margin-bottom: var(--space-4);
  font-size: 0.875rem;
}

.breadcrumbs a {
  color: var(--primary-600);
}

.breadcrumbs .separator {
  margin: 0 var(--space-2);
  color: var(--neutral-400);
}

.breadcrumbs span:last-child {
  color: var(--neutral-500);
}

.subtopic-title {
  font-size: 2.5rem;
  margin-bottom: var(--space-4);
  color: var(--primary-800);
}

.subtopic-meta {
  display: flex;
  gap: var(--space-4);
  color: var(--neutral-600);
  font-size: 0.875rem;
}

.subtopic-meta span {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.table-of-contents {
  background-color: var(--neutral-50);
  border-radius: var(--radius-lg);
  padding: var(--space-4) var(--space-6);
  margin-bottom: var(--space-8);
  border-left: 4px solid var(--primary-500);
}

.table-of-contents h3 {
  font-size: 1.25rem;
  margin-bottom: var(--space-4);
  color: var(--primary-700);
}

.toc-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: var(--space-2) var(--space-6);
}

.toc-list li {
  margin-bottom: var(--space-2);
}

.toc-list a {
  color: var(--neutral-700);
  display: inline-block;
  position: relative;
  padding-left: var(--space-4);
}

.toc-list a::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 6px;
  height: 6px;
  border-radius: var(--radius-full);
  background-color: var(--primary-500);
  transition: all var(--transition-fast);
}

.toc-list a:hover {
  color: var(--primary-700);
}

.toc-list a:hover::before {
  background-color: var(--primary-700);
  width: 8px;
  height: 8px;
}

.subtopic-content {
  margin-top: var(--space-8);
}

.content-section {
  margin-bottom: var(--space-12);
  padding-top: var(--space-4);
}

.content-section h2 {
  font-size: 1.75rem;
  margin-bottom: var(--space-4);
  color: var(--primary-700);
  position: relative;
  padding-bottom: var(--space-2);
  border-bottom: 2px solid var(--neutral-200);
}

.prerequisites-list {
  background-color: var(--neutral-50);
  border-radius: var(--radius-lg);
  padding: var(--space-4) var(--space-6);
}

.prerequisites-list li {
  position: relative;
  padding-left: var(--space-4);
}

.prerequisites-list li::before {
  content: '•';
  position: absolute;
  left: 0;
  color: var(--primary-500);
  font-weight: bold;
}

.code-example {
  margin: var(--space-4) 0;
  background-color: var(--neutral-800);
  border-radius: var(--radius-lg);
  overflow: hidden;
  position: relative;
}

.code-example pre {
  margin: 0;
  padding: var(--space-6);
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.5;
  color: var(--neutral-100);
  overflow-x: auto;
}

.application-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--space-6);
  margin-top: var(--space-4);
}

.application-card {
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.05) 0%, rgba(20, 184, 166, 0.05) 100%);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
  border: 1px solid rgba(59, 130, 246, 0.1);
}

.application-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
  border-color: rgba(59, 130, 246, 0.2);
}

.application-card h3 {
  font-size: 1.25rem;
  margin-bottom: var(--space-2);
  color: var(--primary-700);
}

.industry-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-6);
  margin-top: var(--space-4);
}

.industry-item {
  background-color: var(--neutral-50);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
  transition: all var(--transition);
}

.industry-item:hover {
  background-color: var(--neutral-100);
  transform: translateY(-3px);
}

.industry-item h3 {
  font-size: 1.15rem;
  margin-bottom: var(--space-2);
  color: var(--primary-700);
}

.industry-item ul {
  padding-left: var(--space-4);
  margin-bottom: 0;
}

.resource-item {
  display: flex;
  align-items: center;
  background-color: white;
  padding: var(--space-4);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  margin-bottom: var(--space-4);
  transition: all var(--transition);
  border: 1px solid var(--neutral-200);
}

.resource-item:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary-300);
}

.resource-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  background-color: var(--primary-100);
  color: var(--primary-700);
  border-radius: var(--radius-full);
  margin-right: var(--space-4);
  flex-shrink: 0;
}

.resource-details {
  flex-grow: 1;
}

.resource-details h4 {
  font-size: 1.1rem;
  margin-bottom: var(--space-1);
  color: var(--neutral-900);
}

.resource-details p {
  font-size: 0.9rem;
  color: var(--neutral-600);
  margin-bottom: 0;
}

.resource-link {
  padding: var(--space-2) var(--space-4);
  background-color: var(--primary-600);
  color: white;
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition-fast);
  flex-shrink: 0;
  margin-left: var(--space-4);
}

.resource-link:hover {
  background-color: var(--primary-700);
  color: white;
}

.accordion {
  border: 1px solid var(--neutral-200);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.accordion-item {
  border-bottom: 1px solid var(--neutral-200);
}

.accordion-item:last-child {
  border-bottom: none;
}

.accordion-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  padding: var(--space-4) var(--space-6);
  background-color: white;
  text-align: left;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-weight: 600;
  color: var(--neutral-800);
}

.accordion-header:hover {
  background-color: var(--neutral-50);
}

.accordion-header span {
  flex-grow: 1;
}

.accordion-header svg {
  transition: transform var(--transition-fast);
  flex-shrink: 0;
}

.accordion-item.active .accordion-header {
  background-color: var(--primary-50);
  color: var(--primary-800);
}

.accordion-item.active .accordion-header svg {
  transform: rotate(180deg);
}

.accordion-content {
  padding: 0;
  max-height: 0;
  overflow: hidden;
  transition: all var(--transition);
}

.accordion-item.active .accordion-content {
  padding: var(--space-4) var(--space-6);
  max-height: 500px;
}

/* Responsive Styles */
@media (max-width: 768px) {
  .subtopic-title {
    font-size: 2rem;
  }
  
  .toc-list {
    grid-template-columns: 1fr;
  }
  
  .application-cards, .industry-grid {
    grid-template-columns: 1fr;
  }
  
  .resource-item {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .resource-icon {
    margin-bottom: var(--space-2);
  }
  
  .resource-link {
    margin-left: 0;
    margin-top: var(--space-2);
    width: 100%;
    text-align: center;
  }
}

/* Glassmorphism effect */
.content-section {
  position: relative;
  z-index: 1;
}

.section-description, .section-real-world, .section-applications, .section-resources {
  position: relative;
  background: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-radius: var(--radius-xl);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.2);
  padding: var(--space-6);
}

.section-description::before, .section-real-world::before, 
.section-applications::before, .section-resources::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.05) 0%, rgba(20, 184, 166, 0.05) 100%);
  border-radius: var(--radius-xl);
  z-index: -1;
}

/* Animation for accordion */
.accordion-item {
  transition: all var(--transition);
}

.accordion-header:active {
  transform: scale(0.98);
}

/* Code highlighting */
.code-example pre {
  padding-top: var(--space-8);
  position: relative;
}

.code-example pre::before {
  content: 'Python';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  padding: var(--space-2) var(--space-4);
  background-color: rgba(0, 0, 0, 0.2);
  color: var(--neutral-300);
  font-family: var(--font-main);
  font-size: 0.8rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}