/* Main Subject-specific Styles for History */
:root {
  --history-primary: #8B4513;
  --history-secondary: #A0522D;
  --history-accent: #CD853F;
  --history-light: #F5F0E6;
  --history-dark: #654321;
  --history-gray: #665442;
  --history-gradient-start: rgba(177, 95, 1, 0.9);
  --history-gradient-end: rgba(255, 143, 0, 0.85);
}

/* Subject Hero Section */
.subject-hero {
  position: relative;
  padding: var(--spacing-xxl) 0;
  overflow: hidden;
  background: linear-gradient(135deg, var(--history-light) 0%, rgba(245, 240, 230, 0.8) 100%);
}

.subject-hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image: linear-gradient(to right, var(--history-gradient-start), var(--history-gradient-end)), 
                    url('../../assets/images/history-image.svg');
  background-size: cover;
  background-position: center;
  opacity: 0.9;
  z-index: 0;
}

.subject-hero-content {
  position: relative;
  z-index: 1;
  max-width: 900px;
  margin-bottom: var(--spacing-lg);
}

.subject-hero-content h1 {
  font-size: 3rem;
  color: var(--history-dark);
  margin-bottom: 1.5rem;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.subject-hero-content .gradient-text {
  background: linear-gradient(90deg, var(--history-primary), var(--history-secondary));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.subject-hero-content .subject-description {
  font-size: 1.2rem;
  color: var(--text-light);
  margin-bottom: var(--spacing-lg);
  line-height: 1.6;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
}

.subject-hero-image {
  position: relative;
  z-index: 1;
  text-align: center;
}

.subject-hero-image img {
  max-width: 100%;
  height: 150px; /* 设置固定高度 */
  object-fit: cover; /* 确保图片按比例缩放，可能裁剪图片 */
  filter: drop-shadow(0 10px 20px rgba(0, 0, 0, 0.2));
  animation: float 6s ease-in-out infinite;
}

@keyframes float {
  0% { transform: translateY(0px); }
  50% { transform: translateY(-20px); }
  100% { transform: translateY(0px); }
}

/* Topics Section */
.topics-section {
  padding: 4rem 0;
  background-color: white;
}

.section-header {
  text-align: center;
  margin-bottom: 3rem;
}

.section-header h2 {
  font-size: 2.5rem;
  color: var(--history-dark);
  margin-bottom: 1rem;
  position: relative;
  display: inline-block;
}

.section-header p {
  font-size: 1.2rem;
  color: var(--history-gray);
  max-width: 800px;
  margin: 0 auto;
  line-height: 1.6;
}

.section-header .gradient-text {
  background: linear-gradient(90deg, var(--history-primary), var(--history-secondary));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.topic-card {
  background-color: white;
  border-radius: 10px;
  padding: 2rem;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
  transition: all 0.3s ease;
  border-left: 4px solid var(--history-accent);
}

.topic-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
  border-left: 4px solid var(--history-secondary);
}

.topic-icon {
  font-size: 2.5rem;
  color: var(--history-accent);
  margin-bottom: 1.5rem;
  background-color: rgba(139, 69, 19, 0.1);
}

.topic-icon img {
  width: 64px;
  height: 64px;
  object-fit: contain;
}

.topic-card h3 {
  font-size: 1.5rem;
  color: var(--history-dark);
  margin-bottom: 1rem;
  font-weight: 600;
}

.topic-card p {
  font-size: 1rem;
  color: var(--history-gray);
  line-height: 1.6;
}

/* AI Assistant Section */
.ai-assistant-section {
  padding: var(--spacing-xxl) 0;
  background-color: var(--bg-color);
  position: relative;
}

.assistant-container {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 2rem;
  margin-top: 2rem;
}

.chat-container {
  background: white;
  border-radius: 15px;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.12);
  overflow: hidden;
  height: 500px;
  display: flex;
  flex-direction: column;
  margin-top: 2rem;
  border: 1px solid rgba(177, 95, 1, 0.2);
}

.chat-header {
  padding: 1rem 1.5rem;
  background-color: var(--history-primary);
  color: white;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.chat-header img {
  width: 32px;
  height: 32px;
  object-fit: contain;
}

.chat-header h3 {
  font-size: 1.2rem;
  margin: 0;
  font-weight: 600;
}

.chat-messages {
  flex: 1;
  padding: 1.5rem;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.message {
  max-width: 80%;
  padding: 1rem 1.5rem;
  border-radius: 15px;
  position: relative;
}

.message p {
  margin: 0;
  line-height: 1.5;
  font-size: 1rem;
  color: #333;
  white-space: pre-wrap;
}

.message-user {
  align-self: flex-end;
  background-color: var(--history-accent);
}

.message-user p {
  color: white;
  font-weight: 500;
}

.message-ai p {
  color: #333;
  font-weight: 400;
}

.message-loading p {
  color: #666;
  font-style: italic;
}

.message-loading p::after {
  content: "...";
  animation: dots 1.5s infinite;
}

.message-error p {
  color: #d32f2f;
}

.chat-input {
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  border-top: 1px solid rgba(0, 0, 0, 0.1);
}

.chat-input input {
  flex: 1;
  padding: 0.8rem 1.2rem;
  border: 1px solid rgba(0, 0, 0, 0.1);
  border-radius: 30px;
  font-size: 1rem;
  outline: none;
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
  background-color: #f9f9f9;
}

.chat-input input:focus {
  border-color: var(--history-accent);
  box-shadow: 0 0 0 3px rgba(255, 143, 0, 0.2);
}

.chat-input button {
  background-color: var(--history-accent);
  color: white;
  border: none;
  border-radius: 50%;
  width: 46px;
  height: 46px;
  font-size: 1.2rem;
  cursor: pointer;
  transition: background-color 0.3s;
}

.assistant-features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.feature-item {
  background-color: white;
  padding: 2rem;
  border-radius: 15px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  text-align: center;
  border-bottom: 4px solid var(--history-accent);
}

.feature-item:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.12);
}

.feature-icon {
  margin-bottom: 1.5rem;
}

.feature-icon img {
  width: 64px;
  height: 64px;
  object-fit: contain;
}

.feature-content h4 {
  font-size: 1.5rem;
  color: var(--history-dark);
  margin-bottom: 1rem;
  font-weight: 600;
}

.feature-content p {
  font-size: 1rem;
  color: var(--history-gray);
  line-height: 1.6;
}

/* Quiz Section */
.quiz-section {
  padding: 5rem 0;
  background-color: white;
}

.quiz-container {
  margin-top: 2rem;
}

.quiz-generator {
  background-color: white;
  border-radius: 15px;
  padding: 2rem;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
  margin-top: 2rem;
}

.quiz-controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}

.form-group {
  margin-bottom: 1rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
  color: var(--history-dark);
  font-size: 0.95rem;
}

.form-control {
  width: 100%;
  padding: 0.8rem 1rem;
  border: 1px solid rgba(0, 0, 0, 0.15);
  border-radius: 8px;
  font-size: 1rem;
  background-color: #f9f9f9;
  color: #333;
  outline: none;
  transition: border-color 0.3s, box-shadow 0.3s;
}

.form-control:focus {
  border-color: var(--history-accent);
  box-shadow: 0 0 0 3px rgba(255, 143, 0, 0.2);
}

.quiz-questions {
  background-color: white;
  border-radius: 15px;
  padding: 2rem;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
  margin-top: 2rem;
}

.quiz-questions h3 {
  font-size: 1.8rem;
  color: var(--history-dark);
  margin-bottom: 1.5rem;
  text-align: center;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--history-light);
}

.question-item {
  margin-bottom: 2rem;
  border-bottom: 1px solid rgba(0, 0, 0, 0.1);
  padding-bottom: 1.5rem;
}

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

.question-item h4 {
  font-size: 1.2rem;
  color: var(--history-dark);
  margin-bottom: 1rem;
  font-weight: 600;
}

.options-list {
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}

.option-item {
  display: flex;
  align-items: center;
  padding: 0.8rem 1.2rem;
  background-color: #f9f9f9;
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.3s;
}

.option-item:hover {
  background-color: #f0f0f0;
}

.option-item.selected {
  background-color: var(--history-light);
}

.quiz-actions {
  margin: 1rem 0;
  text-align: center;
}

.btn-small {
  padding: 0.5rem 1rem;
  font-size: 0.9rem;
}

.quiz-feedback {
  margin: 1rem 0;
  padding: 1rem;
  background-color: #f8f9fa;
  border-radius: 0.5rem;
}

.answer-feedback h4 {
  color: #2c3e50;
  margin-bottom: 0.5rem;
}

.answer-feedback .explanation {
  color: #666;
  line-height: 1.5;
}

.quiz-option.correct {
  background-color: #d4edda;
  border-color: #c3e6cb;
}

.quiz-option.incorrect {
  background-color: #f8d7da;
  border-color: #f5c6cb;
}

.quiz-option.correct::after,
.quiz-option.incorrect::after {
  content: '';
  display: inline-block;
  margin-left: 0.5rem;
  width: 1rem;
  height: 1rem;
  background-size: contain;
  background-repeat: no-repeat;
  vertical-align: middle;
}

.quiz-option.correct::after {
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="%2328a745"><path d="M9 16.17L4.83 12l-1.42 1.41L9 19 21 7l-1.41-1.41L9 16.17z"/></svg>');
}

.quiz-option.incorrect::after {
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="%23dc3545"><path d="M19 6.41L17.59 5 12 10.59 6.41 5 5 6.41 10.59 12 5 17.59 6.41 19 12 13.41 17.59 19 19 17.59 13.41 12 19 6.41z"/></svg>');
}

.result-summary .grade {
  font-size: 1.2rem;
  font-weight: bold;
  margin: 0.5rem 0;
}

.result-item {
  margin: 1rem 0;
  padding: 1rem;
  border-radius: 0.5rem;
}

.result-item.correct {
  background-color: #d4edda;
  border: 1px solid #c3e6cb;
}

.result-item.incorrect {
  background-color: #f8d7da;
  border: 1px solid #f5c6cb;
}

.result-item .question {
  font-weight: bold;
  margin-bottom: 0.5rem;
}

.result-item .answer,
.result-item .correct-answer,
.result-item .explanation {
  margin: 0.25rem 0;
  padding-left: 1rem;
}

.result-actions {
  margin-top: 2rem;
  text-align: center;
}

.result-actions button {
  margin: 0 0.5rem;
}

.learning-assessment {
  margin-top: 2rem;
  padding: 1.5rem;
  background-color: #f8f9fa;
  border-radius: 0.5rem;
  border: 1px solid #dee2e6;
}

.learning-assessment h4 {
  color: #2c3e50;
  margin-bottom: 1rem;
}

.assessment-content {
  margin: 1rem 0;
  line-height: 1.6;
}

.assessment-content p {
  margin: 0.5rem 0;
}

#close-assessment {
  margin-top: 1rem;
}

/* Timeline Section */
.timeline-section {
  padding: 4rem 0;
  background-color: #f8f9fa;
}

.timeline-controls {
  display: flex;
  gap: 1rem;
  margin-bottom: 2rem;
  align-items: flex-end;
}

.timeline-controls .form-group {
  flex: 1;
}

.timeline-container {
  background-color: #fff;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
  padding: 2rem;
  margin-top: 2rem;
}

.timeline-header {
  text-align: center;
  margin-bottom: 2rem;
}

.timeline-header h3 {
  color: #2a3b4c;
  margin-bottom: 0.5rem;
}

.timeline-period {
  color: #666;
  font-size: 1.1rem;
}

.timeline-content {
  position: relative;
  padding: 2rem 0;
}

.timeline-content::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 2px;
  height: 100%;
  background-color: #e0e0e0;
}

.timeline-event {
  position: relative;
  margin-bottom: 2rem;
  width: 50%;
  padding: 0 2rem;
}

.timeline-event.left {
  margin-left: 0;
  margin-right: auto;
}

.timeline-event.right {
  margin-left: auto;
  margin-right: 0;
}

.event-year {
  position: absolute;
  top: 0;
  width: 80px;
  height: 80px;
  border-radius: 50%;
  background: linear-gradient(135deg, #4361ee, #7209b7);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  font-size: 1.2rem;
  box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.timeline-event.left .event-year {
  right: -40px;
}

.timeline-event.right .event-year {
  left: -40px;
}

.event-content {
  background-color: #fff;
  border-radius: 8px;
  padding: 1.5rem;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
  position: relative;
}

.event-content h4 {
  color: #2a3b4c;
  margin-bottom: 0.5rem;
}

.event-description {
  color: #666;
  margin-bottom: 1rem;
}

.event-significance {
  background-color: #f8f9fa;
  padding: 1rem;
  border-radius: 4px;
  margin-top: 1rem;
}

.event-significance strong {
  color: #2a3b4c;
}

.timeline-actions {
  text-align: center;
  margin-top: 2rem;
}

/* Responsive styles */
@media (max-width: 768px) {
  .timeline-content::before {
    left: 30px;
  }
  
  .timeline-event {
    width: 100%;
    padding-left: 60px;
    padding-right: 0;
  }
  
  .timeline-event.left,
  .timeline-event.right {
    margin-left: 0;
    margin-right: 0;
  }
  
  .timeline-event.left .event-year,
  .timeline-event.right .event-year {
    left: -40px;
    right: auto;
  }
}

/* Print styles */
@media print {
  .timeline-section {
    padding: 0;
    background-color: #fff;
  }
  
  .timeline-container {
    box-shadow: none;
    padding: 0;
  }
  
  .event-content {
    box-shadow: none;
    border: 1px solid #ddd;
  }
  
  .timeline-actions {
    display: none;
  }
}

/* Sources Section */
.sources-section {
  padding: 5rem 0;
  background-color: white;
}

.sources-container {
  margin-top: 2rem;
}

.sources-controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2rem;
  padding: 1.5rem;
  background-color: var(--history-light);
  border-radius: 15px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
}

.sources-analysis {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  margin-top: 2rem;
}

.source-document {
  background-color: white;
  border-radius: 15px;
  padding: 2rem;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
}

.source-document h3 {
  font-size: 1.5rem;
  color: var(--history-dark);
  margin-bottom: 1.5rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--history-light);
}

.document-content {
  max-height: 400px;
  overflow-y: auto;
  padding-right: 1rem;
  font-size: 1rem;
  line-height: 1.6;
  color: #333;
  white-space: pre-wrap;
  font-family: 'Georgia', serif;
}

.source-metadata {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1.5rem;
}

.metadata-tag {
  display: inline-block;
  padding: 0.3rem 0.8rem;
  background-color: var(--history-light);
  border-radius: 30px;
  font-size: 0.9rem;
  color: var(--history-dark);
  font-weight: 500;
}

.source-breakdown {
  background-color: white;
  border-radius: 15px;
  padding: 2rem;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
}

.source-breakdown h3 {
  font-size: 1.5rem;
  color: var(--history-dark);
  margin-bottom: 1.5rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--history-light);
}

.analysis-section {
  margin-bottom: 1.5rem;
}

.analysis-section h4 {
  font-size: 1.2rem;
  color: var(--history-dark);
  margin-bottom: 1rem;
  font-weight: 600;
}

.analysis-section p {
  font-size: 1rem;
  line-height: 1.6;
  color: #333;
}

.analysis-points {
  margin-top: 1rem;
  padding-left: 1.5rem;
}

.analysis-point {
  position: relative;
  margin-bottom: 1rem;
  padding-left: 2rem;
  font-size: 1rem;
  line-height: 1.6;
  color: #333;
}

.analysis-point::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.5rem;
  width: 10px;
  height: 10px;
  background-color: var(--history-accent);
  border-radius: 50%;
}

@keyframes dots {
  0%, 20% { content: "."; }
  40% { content: ".."; }
  60%, 100% { content: "..."; }
}

.loading {
  text-align: center;
  padding: 2rem;
  font-style: italic;
  color: #666;
}

.error {
  text-align: center;
  padding: 2rem;
  color: #d32f2f;
  font-weight: 500;
}

/* Source Cards Grid */
.sources-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 2rem;
  margin: 2rem 0;
}

.source-card {
  background-color: white;
  border-radius: 10px;
  padding: 2rem;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  border-top: 4px solid var(--history-accent);
  text-align: center;
}

.source-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

.source-card h3 {
  font-size: 1.4rem;
  color: var(--history-dark);
  margin-bottom: 1rem;
  font-weight: 600;
}

.source-card p {
  font-size: 1rem;
  color: var(--history-gray);
  line-height: 1.6;
  margin-bottom: 1.5rem;
}

.source-analysis-demo {
  margin-top: 4rem;
}

.source-analysis-container {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 2rem;
  margin-top: 1.5rem;
}

.source-display {
  background-color: white;
  border-radius: 15px;
  padding: 2rem;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
  min-height: 300px;
}

.source-placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  text-align: center;
}

.source-controls {
  background-color: var(--history-light);
  border-radius: 15px;
  padding: 2rem;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
}

.source-example h4 {
  font-size: 1.3rem;
  color: var(--history-dark);
  margin-bottom: 1.5rem;
  text-align: center;
}

.source-image-placeholder {
  width: 100%;
  height: 200px;
  background-color: #f0f0f0;
  border-radius: 8px;
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #999;
  font-style: italic;
}

.source-description {
  font-size: 1rem;
  line-height: 1.6;
  color: #333;
  margin-bottom: 1.5rem;
}

.source-analysis h5 {
  font-size: 1.1rem;
  color: var(--history-dark);
  margin-bottom: 1rem;
  font-weight: 600;
}

.source-analysis ul {
  padding-left: 1.5rem;
}

.source-analysis li {
  font-size: 1rem;
  line-height: 1.6;
  color: #333;
  margin-bottom: 0.5rem;
}

/* Responsive */
@media (max-width: 992px) {
  .sources-analysis {
    grid-template-columns: 1fr;
  }
  
  .subject-hero-content h1 {
    font-size: 2.5rem;
  }
  
  .timeline-event {
    width: 100%;
    margin-left: 0 !important;
    padding-left: 40px;
  }
  
  .timeline-event:nth-child(odd),
  .timeline-event:nth-child(even) {
    margin-left: 0;
  }
  
  .timeline-line {
    left: 10px;
    transform: none;
  }
  
  .timeline-event:nth-child(odd) .timeline-date,
  .timeline-event:nth-child(even) .timeline-date {
    position: relative;
    left: 0;
    right: 0;
    text-align: left;
    margin-bottom: 1rem;
    top: 0;
  }
  
  .source-analysis-container {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .subject-hero-content h1 {
    font-size: 2rem;
  }
  
  .section-header h2 {
    font-size: 2rem;
  }
  
  .assistant-features {
    grid-template-columns: 1fr;
  }
  
  .chat-messages {
    height: 350px;
  }
  
  .message {
    max-width: 90%;
  }
  
  .timeline-event:nth-child(odd) .timeline-date,
  .timeline-event:nth-child(even) .timeline-date {
    position: relative;
    left: 0;
    right: 0;
    text-align: left;
    margin-bottom: 1rem;
    font-size: 0.9rem;
  }
}

/* Source Analysis Section */
.source-section {
    padding: var(--spacing-xxl) 0;
}

.source-container {
    background-color: var(--bg-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
}

.source-selector {
    margin-bottom: var(--spacing-lg);
}

.source-content {
    min-height: 400px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--bg-dark);
    border-radius: var(--border-radius-md);
    padding: var(--spacing-lg);
}

/* Source Document Styling */
.document-display {
    max-width: 700px;
    margin: 0 auto;
}

.document-card {
    background-color: white;
    border-radius: var(--border-radius-md);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    border-left: 5px solid var(--history-primary);
}

.document-header {
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

.document-title {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-xs);
    color: var(--history-dark);
}

.document-metadata {
    color: var(--text-light);
    font-style: italic;
    margin-bottom: var(--spacing-sm);
}

.document-content {
    font-family: 'Georgia', serif;
    line-height: 1.8;
    color: var(--text-color);
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-md);
    background-color: var(--history-light);
    border-radius: var(--border-radius-sm);
}

.analysis-questions {
    margin-top: var(--spacing-lg);
    border-top: 1px solid var(--bg-light);
    padding-top: var(--spacing-md);
}

.analysis-questions h4 {
    color: var(--history-primary);
    margin-bottom: var(--spacing-sm);
}

.analysis-questions ul {
    list-style-type: disc;
    padding-left: var(--spacing-lg);
    color: var(--text-light);
}

.analysis-questions li {
    margin-bottom: var(--spacing-xs);
}

/* Placeholder Content */
.placeholder-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: var(--spacing-xl);
}

.placeholder-content img {
    max-width: 200px;
    margin-bottom: var(--spacing-lg);
}

.placeholder-content p {
    color: var(--text-light);
    max-width: 500px;
    line-height: 1.6;
}

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

@keyframes pulse {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
    100% {
        transform: scale(1);
    }
}

.timeline-marker {
    animation: pulse 2s infinite ease-in-out;
}

/* Custom button styles */
.btn-primary {
    background-color: var(--history-primary);
    border-color: var(--history-primary);
}

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

/* Quiz section customization */
.quiz-section .btn-primary {
    background-color: var(--history-primary);
    border-color: var(--history-primary);
}

.quiz-option.selected {
    background-color: var(--history-secondary);
    border-color: var(--history-secondary);
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .timeline::before {
        left: 30px;
    }
    
    .timeline-event {
        width: calc(100% - 60px);
        margin-left: 60px !important;
    }
    
    .document-content {
        padding: var(--spacing-sm);
    }
}