:root {
  --oop-primary: #0d9488;
  --oop-secondary: #2dd4bf;
  --oop-gradient: linear-gradient(135deg, #0f766e 0%, #2dd4bf 100%);
  --oop-bg: rgba(13, 148, 136, 0.06);
  --oop-bg-hover: rgba(13, 148, 136, 0.12);
}

.typing-text_oop {
  color: var(--oop-secondary);
  font-weight: 600;
}

.oop-layout {
  display: flex;
  gap: 2rem;
  align-items: flex-start;
}

.oop-sidebar {
  position: sticky;
  top: 100px;
  width: 240px;
  flex-shrink: 0;
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  padding: 1.25rem 0;
  backdrop-filter: blur(10px);
}

.oop-sidebar-title {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-secondary);
  padding: 0 1.25rem 0.75rem;
  border-bottom: 1px solid var(--glass-border);
  margin-bottom: 0.5rem;
}

.oop-sidebar-nav {
  list-style: none;
  padding: 0;
  margin: 0;
}

.oop-sidebar-nav li a {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.55rem 1.25rem;
  font-size: 0.85rem;
  color: var(--text-secondary);
  text-decoration: none;
  transition: all 0.2s ease;
  border-left: 3px solid transparent;
}

.oop-sidebar-nav li a:hover,
.oop-sidebar-nav li a.active {
  color: var(--oop-secondary);
  background: var(--oop-bg);
  border-left-color: var(--oop-primary);
}

.oop-sidebar-nav li a .nav-icon {
  width: 20px;
  text-align: center;
  font-size: 0.9rem;
}

.oop-main-content {
  flex: 1;
  min-width: 0;
}

.oop-lesson {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  padding: 2.5rem;
  margin-bottom: 2rem;
  backdrop-filter: blur(10px);
  transition: border-color 0.3s ease;
}

.oop-lesson:target {
  border-color: var(--oop-primary);
}

.oop-lesson-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.oop-lesson-number {
  font-family: "Orbitron", sans-serif;
  font-size: 1.5rem;
  font-weight: 700;
  background: var(--oop-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  flex-shrink: 0;
}

.oop-lesson-header h3 {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0;
}

.oop-lesson p,
.oop-lesson li {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.75;
  margin-bottom: 0.75rem;
}

.oop-lesson ul,
.oop-lesson ol {
  padding-left: 1.5rem;
  margin-bottom: 1rem;
}

.oop-lesson li {
  margin-bottom: 0.4rem;
}

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

.oop-concept-card {
  background: var(--dark-surface);
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  padding: 1.25rem 1.5rem;
  margin: 1rem 0;
}

.oop-concept-card h4 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--oop-secondary);
  margin: 0 0 0.5rem;
}

.oop-concept-card p {
  margin-bottom: 0;
}

.oop-code-block {
  position: relative;
  margin: 1rem 0 1.5rem;
  border-radius: 12px;
  overflow: hidden;
  border: 1px solid var(--glass-border);
}

.oop-code-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: rgba(0, 0, 0, 0.3);
  padding: 0.5rem 1rem;
  border-bottom: 1px solid var(--glass-border);
}

.oop-code-lang {
  font-family: "Fira Code", monospace;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--oop-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.oop-code-copy {
  background: none;
  border: 1px solid var(--glass-border);
  color: var(--text-secondary);
  font-size: 0.75rem;
  padding: 0.25rem 0.6rem;
  border-radius: 6px;
  cursor: pointer;
  font-family: "Poppins", sans-serif;
  transition: all 0.2s ease;
}

.oop-code-copy:hover {
  color: var(--text-primary);
  border-color: var(--oop-secondary);
}

.oop-code-copy.copied {
  color: #2dd4bf;
  border-color: #2dd4bf;
}

.oop-code-block pre {
  margin: 0;
  padding: 1.25rem 1.5rem;
  background: #0d1117;
  overflow-x: auto;
}

.oop-code-block code {
  font-family: "Fira Code", Consolas, Monaco, monospace;
  font-size: 0.85rem;
  line-height: 1.7;
  color: #e6edf3;
}

/* Pseudocode custom highlighting */
.oop-code-block .tok-kw { color: #ff79c6; font-weight: bold; }
.oop-code-block .tok-fn { color: #50fa7b; }
.oop-code-block .tok-str { color: #f1fa8c; }
.oop-code-block .tok-num { color: #bd93f9; }
.oop-code-block .tok-cmt { color: #6272a4; font-style: italic; }
.oop-code-block .tok-op { color: #ff79c6; }
.oop-code-block .tok-bi { color: #8be9fd; }
.oop-code-block .tok-var { color: #f8f8f2; }
.oop-code-block .tok-bool { color: #bd93f9; }
.oop-code-block .tok-param { color: #ffb86c; }
.oop-code-block .tok-pch { color: #ffb86c; }

.oop-exercise {
  background: rgba(45, 212, 191, 0.06);
  border: 1px solid rgba(45, 212, 191, 0.25);
  border-radius: 12px;
  padding: 1.5rem;
  margin: 1.5rem 0;
}

.oop-exercise-title {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1rem;
  font-weight: 600;
  color: var(--oop-secondary);
  margin-bottom: 0.75rem;
}

.oop-exercise-title i {
  font-size: 1.1rem;
}

.oop-exercise ol,
.oop-exercise ul {
  margin-bottom: 0.75rem;
}

.oop-exercise-toggle {
  background: rgba(45, 212, 191, 0.15);
  border: 1px solid rgba(45, 212, 191, 0.3);
  color: var(--oop-secondary);
  font-family: "Poppins", sans-serif;
  font-size: 0.85rem;
  font-weight: 500;
  padding: 0.4rem 1rem;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.oop-exercise-toggle:hover {
  background: rgba(45, 212, 191, 0.25);
}

.oop-exercise-solution {
  display: none;
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid rgba(45, 212, 191, 0.2);
}

.oop-exercise-solution.visible {
  display: block;
}

.oop-exercise-solution p {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
}

.oop-progress-bar {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin: 2rem 0;
  padding: 1.25rem 1.5rem;
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  backdrop-filter: blur(10px);
}

.oop-progress-track {
  flex: 1;
  height: 8px;
  background: var(--dark-surface);
  border-radius: 99px;
  overflow: hidden;
}

.oop-progress-fill {
  height: 100%;
  width: 0%;
  background: var(--oop-gradient);
  border-radius: 99px;
  transition: width 0.5s ease;
}

.oop-progress-text {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
}

.oop-callout {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
  background: var(--oop-bg);
  border: 1px solid rgba(13, 148, 136, 0.25);
  border-radius: 12px;
  padding: 1.25rem 1.5rem;
  margin: 1.25rem 0;
}

.oop-callout-icon {
  font-size: 1.3rem;
  flex-shrink: 0;
  line-height: 1.4;
}

.oop-callout p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.6;
}

/* Vector Diagram Styles */
.oop-svg-container {
  display: flex;
  justify-content: center;
  background: rgba(0, 0, 0, 0.2);
  border-radius: 12px;
  padding: 1.5rem;
  margin: 1.5rem 0;
  border: 1px solid var(--glass-border);
}

.oop-svg-diagram {
  max-width: 100%;
  height: auto;
}

.oop-svg-node {
  fill: var(--dark-surface);
  stroke: var(--glass-border);
  stroke-width: 1.5;
  rx: 8;
  ry: 8;
  transition: all 0.3s ease;
}

.oop-svg-node:hover {
  stroke: var(--oop-secondary);
}

.oop-svg-node-highlight {
  fill: rgba(13, 148, 136, 0.15);
  stroke: var(--oop-secondary);
  stroke-width: 2;
  rx: 8;
  ry: 8;
}

.oop-svg-line {
  stroke: var(--text-secondary);
  stroke-width: 1.5;
  stroke-dasharray: 4, 4;
  fill: none;
}

.oop-svg-line-solid {
  stroke: var(--oop-secondary);
  stroke-width: 2;
  fill: none;
}

.oop-svg-text {
  fill: var(--text-primary);
  font-family: "Poppins", sans-serif;
  font-size: 0.8rem;
  text-anchor: middle;
  dominant-baseline: middle;
}

.oop-svg-text-bold {
  fill: var(--oop-secondary);
  font-family: "Orbitron", sans-serif;
  font-size: 0.85rem;
  font-weight: 700;
  text-anchor: middle;
  dominant-baseline: middle;
}

/* Quiz Styles */
.oop-quiz-container {
  display: flex;
  flex-direction: column;
  gap: 1.75rem;
}

.oop-quiz-question-card {
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  padding: 1.5rem;
}

.oop-quiz-question-text {
  font-weight: 600;
  font-size: 1rem;
  color: var(--text-primary);
  margin-bottom: 1rem;
  display: flex;
  gap: 0.5rem;
}

.oop-quiz-question-num {
  color: var(--oop-secondary);
  font-family: "Orbitron", sans-serif;
}

.oop-quiz-options {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.oop-quiz-option {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--glass-border);
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s ease;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.oop-quiz-option:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.2);
}

.oop-quiz-option.selected {
  background: var(--oop-bg);
  border-color: var(--oop-secondary);
  color: var(--text-primary);
}

.oop-quiz-option.correct {
  background: rgba(16, 185, 129, 0.1);
  border-color: #10b981;
  color: #10b981;
}

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

.oop-quiz-option input[type="radio"] {
  accent-color: var(--oop-secondary);
  cursor: pointer;
}

.oop-quiz-feedback {
  font-size: 0.85rem;
  font-weight: 600;
  display: none;
  margin-bottom: 0.5rem;
}

.oop-quiz-feedback.correct {
  display: block;
  color: #10b981;
}

.oop-quiz-feedback.incorrect {
  display: block;
  color: #ef4444;
}

.oop-quiz-explanation {
  display: none;
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.5;
  border-left: 3px solid var(--oop-primary);
  padding-left: 0.75rem;
  margin-top: 0.5rem;
}

.oop-quiz-explanation.visible {
  display: block;
}

.oop-quiz-actions {
  display: flex;
  gap: 1rem;
  margin-top: 1rem;
}

.oop-quiz-btn {
  background: var(--oop-gradient);
  border: none;
  color: white;
  padding: 0.6rem 1.5rem;
  border-radius: 8px;
  font-family: "Poppins", sans-serif;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  box-shadow: 0 4px 12px rgba(13, 148, 136, 0.2);
}

.oop-quiz-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(13, 148, 136, 0.35);
}

.oop-quiz-btn-secondary {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--glass-border);
  color: var(--text-primary);
  padding: 0.6rem 1.5rem;
  border-radius: 8px;
  font-family: "Poppins", sans-serif;
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
}

.oop-quiz-btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.2);
}

.oop-quiz-score-banner {
  display: none;
  background: var(--oop-bg);
  border: 1px solid var(--oop-secondary);
  border-radius: 12px;
  padding: 1.5rem;
  text-align: center;
  margin-top: 1.5rem;
}

.oop-quiz-score-banner.visible {
  display: block;
}

.oop-quiz-score-title {
  font-family: "Orbitron", sans-serif;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--oop-secondary);
  margin-bottom: 0.5rem;
}

.oop-quiz-score-text {
  font-size: 0.95rem;
  color: var(--text-secondary);
}

@media (max-width: 1024px) {
  .oop-sidebar {
    display: none;
  }
}

@media (max-width: 768px) {
  .oop-lesson {
    padding: 1.5rem;
  }

  .oop-lesson-header h3 {
    font-size: 1.15rem;
  }

  .oop-code-block pre {
    padding: 1rem;
  }

  .oop-code-block code {
    font-size: 0.78rem;
  }

  .oop-progress-bar {
    flex-direction: column;
    align-items: stretch;
    gap: 0.5rem;
  }

  .oop-progress-text {
    text-align: center;
  }

  .oop-callout {
    flex-direction: column;
    gap: 0.5rem;
  }
}

@media (max-width: 480px) {
  .oop-lesson {
    padding: 1.25rem;
    border-radius: 12px;
  }

  .oop-lesson-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }

  .oop-exercise {
    padding: 1rem;
  }
}

.oop-sidebar-nav li a:focus-visible,
.oop-code-copy:focus-visible,
.oop-exercise-toggle:focus-visible,
.oop-quiz-option:focus-visible,
.oop-quiz-btn:focus-visible {
  outline: 2px solid var(--oop-secondary);
  outline-offset: 2px;
}

@media print {
  .oop-sidebar,
  .oop-progress-bar,
  .oop-exercise-toggle,
  .oop-code-copy,
  .oop-quiz-actions,
  .navbar,
  .footer {
    display: none !important;
  }

  .oop-lesson {
    break-inside: avoid;
    border: 1px solid #ccc;
  }

  .oop-code-block pre {
    background: #f5f5f5;
    color: #333;
  }
}