/**
 * Lesson Viewer Styles
 * Premium, engaging design for interactive learning experience
 */

.lesson-viewer {
  max-width: 900px;
  margin: 0 auto;
  padding: var(--space-8) var(--space-6);
}

/* ==================== Lesson Header ==================== */

.lesson-breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: var(--space-6);
  font-size: 0.875rem;
  color: var(--text-tertiary);
}

.breadcrumb-link {
  color: var(--brand);
  text-decoration: none;
  transition: color 0.2s ease;
}

.breadcrumb-link:hover {
  color: var(--brand-light);
}

.breadcrumb-separator {
  opacity: 0.5;
}

.breadcrumb-current {
  color: var(--text-secondary);
}

.lesson-header {
  margin-bottom: var(--space-10);
}

.lesson-header-content {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

.lesson-title {
  font-family: var(--font-display);
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0 0 var(--space-3) 0;
  letter-spacing: -0.025em;
  line-height: 1.2;
}

.lesson-subtitle {
  font-size: 1.125rem;
  color: var(--text-secondary);
  margin: 0 0 var(--space-6) 0;
  line-height: 1.6;
}

.lesson-meta {
  display: flex;
  gap: var(--space-6);
  flex-wrap: wrap;
}

.lesson-meta-item {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: 0.875rem;
  color: var(--text-tertiary);
}

.lesson-meta-item svg {
  opacity: 0.7;
}

.lesson-meta-difficulty {
  text-transform: capitalize;
  padding: var(--space-1) var(--space-3);
  background: rgba(var(--brand-rgb, 6, 182, 212), 0.1);
  border-radius: var(--radius-md);
  color: var(--brand);
  font-weight: 600;
}

/* ==================== Lesson Content ==================== */

.lesson-content {
  margin-bottom: var(--space-10);
}

.lesson-section {
  margin-bottom: var(--space-10);
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.lesson-section-heading {
  font-family: var(--font-display);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0 0 var(--space-6) 0;
  letter-spacing: -0.025em;
}

.lesson-section-content {
  color: var(--text-secondary);
  line-height: 1.8;
  font-size: 1.0625rem;
}

.lesson-section-content p {
  margin-bottom: var(--space-4);
}

.lesson-section-content h1,
.lesson-section-content h2,
.lesson-section-content h3 {
  font-family: var(--font-display);
  color: var(--text-primary);
  margin: var(--space-8) 0 var(--space-4) 0;
  font-weight: 600;
}

.lesson-section-content h1 {
  font-size: 2rem;
}

.lesson-section-content h2 {
  font-size: 1.5rem;
}

.lesson-section-content h3 {
  font-size: 1.25rem;
}

.lesson-section-content ul {
  list-style: none;
  padding-left: 0;
  margin: var(--space-4) 0;
}

.lesson-section-content ul li {
  position: relative;
  padding-left: var(--space-6);
  margin-bottom: var(--space-3);
}

.lesson-section-content ul li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--brand);
  font-weight: 600;
}

.lesson-section-content strong {
  color: var(--text-primary);
  font-weight: 600;
}

/* ==================== Interactive Elements ==================== */

.lesson-interactive-elements {
  margin-top: var(--space-6);
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.lesson-interactive-element {
  display: flex;
  gap: var(--space-4);
  padding: var(--space-5);
  border-radius: var(--radius-md);
  border: 1px solid;
  background: var(--bg-surface);
}

.lesson-interactive-icon {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.05);
}

.lesson-interactive-content {
  flex: 1;
}

.lesson-interactive-content p {
  margin: 0;
}

/* Interactive element types */
.lesson-interactive-tip {
  border-color: rgba(34, 197, 94, 0.3);
  background: rgba(34, 197, 94, 0.05);
}

.lesson-interactive-tip .lesson-interactive-icon {
  background: rgba(34, 197, 94, 0.1);
  color: #22c55e;
}

.lesson-interactive-warning {
  border-color: rgba(251, 191, 36, 0.3);
  background: rgba(251, 191, 36, 0.05);
}

.lesson-interactive-warning .lesson-interactive-icon {
  background: rgba(251, 191, 36, 0.1);
  color: #fbbf24;
}

.lesson-interactive-example {
  border-color: rgba(59, 130, 246, 0.3);
  background: rgba(59, 130, 246, 0.05);
}

.lesson-interactive-example .lesson-interactive-icon {
  background: rgba(59, 130, 246, 0.1);
  color: #3b82f6;
}

.lesson-interactive-exercise {
  border-color: rgba(168, 85, 247, 0.3);
  background: rgba(168, 85, 247, 0.05);
}

.lesson-interactive-exercise .lesson-interactive-icon {
  background: rgba(168, 85, 247, 0.1);
  color: #a855f7;
}

.lesson-interactive-callout {
  border-color: rgba(var(--brand-rgb, 6, 182, 212), 0.3);
  background: rgba(var(--brand-rgb, 6, 182, 212), 0.05);
}

.lesson-interactive-callout .lesson-interactive-icon {
  background: rgba(var(--brand-rgb, 6, 182, 212), 0.1);
  color: var(--brand);
}

/* ==================== Quiz Section ==================== */

.lesson-quiz-section {
  margin-bottom: var(--space-10);
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.lesson-section-heading-wrapper {
  margin-bottom: var(--space-8);
  padding-bottom: var(--space-6);
  border-bottom: 1px solid var(--border-color);
}

.lesson-quiz-intro {
  margin-top: var(--space-3);
  color: var(--text-tertiary);
  font-size: 0.9375rem;
}

.lesson-quiz {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
  margin-bottom: var(--space-6);
}

.lesson-quiz-question {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: var(--space-6);
  transition: all 0.3s ease;
}

.lesson-quiz-question.answered {
  border-color: rgba(var(--brand-rgb, 6, 182, 212), 0.3);
}

.lesson-quiz-question.correct {
  border-color: rgba(34, 197, 94, 0.5);
  background: rgba(34, 197, 94, 0.05);
}

.lesson-quiz-question.incorrect {
  border-color: rgba(239, 68, 68, 0.5);
  background: rgba(239, 68, 68, 0.05);
}

.lesson-quiz-question-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-4);
}

.lesson-quiz-question-number {
  font-weight: 600;
  color: var(--text-secondary);
  font-size: 0.875rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.lesson-quiz-question-difficulty {
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: capitalize;
}

.lesson-quiz-difficulty-easy {
  background: rgba(34, 197, 94, 0.1);
  color: #22c55e;
}

.lesson-quiz-difficulty-medium {
  background: rgba(251, 191, 36, 0.1);
  color: #fbbf24;
}

.lesson-quiz-difficulty-hard {
  background: rgba(239, 68, 68, 0.1);
  color: #ef4444;
}

.lesson-quiz-question-text {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 0 0 var(--space-5) 0;
  line-height: 1.5;
}

.lesson-quiz-options {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.lesson-quiz-option {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-4);
  background: var(--bg-card);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all 0.2s ease;
}

.lesson-quiz-option:hover {
  border-color: var(--brand);
  background: rgba(var(--brand-rgb, 6, 182, 212), 0.05);
}

.lesson-quiz-option input[type="radio"] {
  appearance: none;
  width: 20px;
  height: 20px;
  border: 2px solid var(--border-color);
  border-radius: 50%;
  cursor: pointer;
  position: relative;
  flex-shrink: 0;
}

.lesson-quiz-option input[type="radio"]:checked {
  border-color: var(--brand);
}

.lesson-quiz-option input[type="radio"]:checked::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 10px;
  height: 10px;
  background: var(--brand);
  border-radius: 50%;
}

.lesson-quiz-option.correct-answer {
  border-color: #22c55e;
  background: rgba(34, 197, 94, 0.1);
}

.lesson-quiz-option.wrong-answer {
  border-color: #ef4444;
  background: rgba(239, 68, 68, 0.1);
}

.lesson-quiz-option svg {
  margin-left: auto;
  color: #22c55e;
}

.lesson-quiz-option-text {
  flex: 1;
  color: var(--text-secondary);
  font-size: 1rem;
  line-height: 1.6;
}

.lesson-quiz-explanation {
  margin-top: var(--space-4);
  padding: var(--space-4);
  background: rgba(var(--brand-rgb, 6, 182, 212), 0.05);
  border-left: 3px solid var(--brand);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 0.9375rem;
  line-height: 1.7;
}

.lesson-quiz-explanation strong {
  color: var(--text-primary);
}

.btn-quiz-submit {
  width: 100%;
  font-size: 1.0625rem;
  padding: var(--space-4) var(--space-6);
}

/* ==================== Footer ==================== */

.lesson-footer {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-6);
  margin-bottom: var(--space-10);
}

.lesson-action-items,
.lesson-key-takeaways {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.lesson-action-items-intro {
  color: var(--text-tertiary);
  font-size: 0.9375rem;
  margin-bottom: var(--space-6);
}

.lesson-action-list,
.lesson-takeaway-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.lesson-action-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
  padding: var(--space-3);
  background: var(--bg-surface);
  border-radius: var(--radius-md);
  transition: background 0.2s ease;
}

.lesson-action-item:hover {
  background: rgba(var(--brand-rgb, 6, 182, 212), 0.05);
}

.lesson-action-checkbox {
  appearance: none;
  width: 20px;
  height: 20px;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-sm);
  cursor: pointer;
  position: relative;
  flex-shrink: 0;
  margin-top: 2px;
}

.lesson-action-checkbox:checked {
  background: var(--brand);
  border-color: var(--brand);
}

.lesson-action-checkbox:checked::after {
  content: '✓';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: white;
  font-size: 0.75rem;
  font-weight: 700;
}

.lesson-takeaway-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
  padding: var(--space-3);
  color: var(--text-secondary);
}

.lesson-takeaway-item svg {
  flex-shrink: 0;
  color: var(--brand);
  margin-top: 2px;
}

/* ==================== Navigation ==================== */

.lesson-navigation {
  display: flex;
  justify-content: space-between;
  gap: var(--space-4);
  padding-top: var(--space-8);
  border-top: 1px solid var(--border-color);
}

.lesson-navigation .btn {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

/* ==================== Responsive ==================== */

@media (max-width: 768px) {
  .lesson-viewer {
    padding: var(--space-6) var(--space-4);
  }

  .lesson-title {
    font-size: 2rem;
  }

  .lesson-subtitle {
    font-size: 1rem;
  }

  .lesson-footer {
    grid-template-columns: 1fr;
  }

  .lesson-navigation {
    flex-direction: column;
  }

  .lesson-navigation .btn:nth-child(2) {
    order: -1;
  }
}

/* ==================== Loading State ==================== */

.lesson-loading {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 50vh;
  color: var(--text-tertiary);
  font-size: 1.125rem;
}

/* ==================== Upgrade Required State ==================== */

.upgrade-required-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--space-10);
  text-align: center;
  max-width: 600px;
  margin: var(--space-10) auto;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

.upgrade-icon {
  font-size: 4rem;
  margin-bottom: var(--space-6);
  opacity: 0.7;
}

.upgrade-required-card h2 {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-4);
}

.upgrade-required-card p {
  font-size: 1.125rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-8);
  line-height: 1.6;
}

.upgrade-actions {
  display: flex;
  gap: var(--space-4);
  justify-content: center;
  flex-wrap: wrap;
}

.upgrade-actions .btn {
  min-width: 180px;
}