/* Shared Lesson Stylesheet - Tufte-inspired clean academic layout */
:root {
  --bg-color: #fcfbf9;
  --text-color: #2c2a29;
  --link-color: #0b63ce;
  --accent-color: #1a4f78;
  --code-bg: #f4f1ea;
  --border-color: #e5e0d8;
  --card-bg: #ffffff;
  --success-color: #1f7a46;
  --warning-color: #b25e00;
  --font-serif: "ETBembo", "Georgia", "Times New Roman", serif;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  font-family: var(--font-serif);
  line-height: 1.68;
  font-size: 19px;
  max-width: 840px;
  margin: 0 auto;
  padding: 40px 24px 100px;
}

header {
  border-bottom: 2px solid var(--border-color);
  padding-bottom: 24px;
  margin-bottom: 36px;
}

.lesson-meta {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: #6c6662;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 8px;
}

h1 {
  font-size: 2.2rem;
  font-weight: 600;
  line-height: 1.25;
  margin: 0 0 12px 0;
  color: var(--accent-color);
}

h2 {
  font-family: var(--font-sans);
  font-size: 1.35rem;
  font-weight: 600;
  margin-top: 48px;
  margin-bottom: 16px;
  color: #1f2937;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 6px;
}

h3 {
  font-family: var(--font-sans);
  font-size: 1.1rem;
  font-weight: 600;
  margin-top: 28px;
  margin-bottom: 12px;
}

p, ul, ol {
  margin: 0 0 20px 0;
}

li {
  margin-bottom: 8px;
}

a {
  color: var(--link-color);
  text-decoration: underline;
  text-underline-offset: 3px;
}

a:hover {
  color: #084996;
}

code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background-color: var(--code-bg);
  padding: 2px 5px;
  border-radius: 4px;
  border: 1px solid #ebd9c8;
}

pre {
  background-color: var(--code-bg);
  padding: 16px 20px;
  border-radius: 6px;
  overflow-x: auto;
  border: 1px solid var(--border-color);
  margin: 20px 0;
}

pre code {
  background: none;
  border: none;
  padding: 0;
  font-size: 0.9em;
  line-height: 1.5;
}

blockquote {
  border-left: 3px solid var(--accent-color);
  margin: 24px 0;
  padding: 8px 0 8px 20px;
  font-style: italic;
  color: #4b4744;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 24px;
  margin: 28px 0;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.02);
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-sans);
  font-size: 0.95rem;
  margin: 24px 0;
}

.comparison-table th,
.comparison-table td {
  padding: 12px 14px;
  border: 1px solid var(--border-color);
  text-align: left;
}

.comparison-table th {
  background-color: #f2eee8;
  font-weight: 600;
}

/* Interactive Quiz Widget */
.quiz-container {
  background: var(--card-bg);
  border: 2px solid var(--accent-color);
  border-radius: 8px;
  padding: 24px;
  margin: 36px 0;
}

.quiz-title {
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 1.15rem;
  margin-bottom: 12px;
  color: var(--accent-color);
}

.quiz-options {
  list-style: none;
  padding: 0;
  margin: 16px 0;
}

.quiz-option {
  margin-bottom: 10px;
}

.quiz-btn {
  display: block;
  width: 100%;
  text-align: left;
  background: var(--code-bg);
  border: 1px solid var(--border-color);
  padding: 12px 16px;
  border-radius: 6px;
  font-family: var(--font-sans);
  font-size: 0.95rem;
  cursor: pointer;
  transition: all 0.15s ease-in-out;
}

.quiz-btn:hover {
  background: #ebe5dc;
}

.quiz-btn.correct {
  background: #e6f4ea;
  border-color: var(--success-color);
  color: #13522c;
  font-weight: 600;
}

.quiz-btn.incorrect {
  background: #fce8e6;
  border-color: #d93025;
  color: #a51d24;
}

.quiz-feedback {
  margin-top: 14px;
  padding: 12px;
  border-radius: 6px;
  font-family: var(--font-sans);
  font-size: 0.92rem;
  display: none;
}

.footer-nav {
  margin-top: 60px;
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
  font-family: var(--font-sans);
  display: flex;
  justify-content: space-between;
  font-size: 0.9rem;
}