/* ============================================
   AI Decoded — Crash Course Styles
   ============================================ */

:root {
  --navy: #1B2A4A;
  --terracotta: #E07A5F;
  --terracotta-dark: #c9664b;
  --gold: #F2CC8F;
  --off-white: #FAFAFA;
  --warm-gray: #F0EDE8;
  --text-primary: #2D3748;
  --text-secondary: #4A5568;
  --text-light: #718096;
  --green: #48BB78;
  --green-bg: #F0FFF4;
  --red: #F56565;
  --red-bg: #FFF5F5;

  --font-body: 'Inter', sans-serif;
  --font-heading: 'Playfair Display', serif;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);
}

/* --- Base --- */
html { scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  color: var(--text-primary);
  background: var(--off-white);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 { font-family: var(--font-heading); color: var(--navy); }

/* --- Hero --- */
.hero-gradient {
  background: linear-gradient(135deg, #1B2A4A 0%, #2d4a7a 40%, #3d5a8a 60%, #1B2A4A 100%);
}

/* --- Progress Bar --- */
.progress-bar-bg {
  background: rgba(255,255,255,0.15);
  border-radius: 999px;
  overflow: hidden;
}

.progress-bar-fill {
  background: var(--terracotta);
  height: 100%;
  border-radius: 999px;
  transition: width 0.5s ease;
}

/* --- Lesson Card --- */
.lesson-card {
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.lesson-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.lesson-card.completed {
  border-left: 4px solid var(--green);
}

/* --- Deep Dive (Expandable) --- */
.deep-dive { margin: 1rem 0; }

.deep-dive-toggle {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--warm-gray);
  border: none;
  padding: 0.75rem 1rem;
  border-radius: 0.5rem;
  cursor: pointer;
  font-family: var(--font-body);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--navy);
  width: 100%;
  text-align: left;
  transition: background 0.2s;
}

.deep-dive-toggle:hover { background: #E8E4DE; }

.deep-dive-toggle svg {
  transition: transform 0.3s ease;
  flex-shrink: 0;
}

.deep-dive-toggle.open svg { transform: rotate(90deg); }

.deep-dive-content {
  display: none;
  padding: 1rem 1.25rem;
  background: var(--warm-gray);
  border-radius: 0 0 0.5rem 0.5rem;
  margin-top: -0.25rem;
  font-size: 0.9rem;
  line-height: 1.7;
  color: var(--text-secondary);
}

.deep-dive-content.open { display: block; }

/* --- Quiz / Knowledge Check --- */
.quiz {
  background: white;
  border: 2px solid #E2E8F0;
  border-radius: 0.75rem;
  padding: 1.5rem;
  margin: 1.5rem 0;
}

.quiz-question {
  font-weight: 600;
  color: var(--navy);
  margin-bottom: 1rem;
  font-size: 1rem;
}

.quiz-options { display: flex; flex-direction: column; gap: 0.5rem; }

.quiz-option {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  border: 2px solid #E2E8F0;
  border-radius: 0.5rem;
  cursor: pointer;
  transition: all 0.2s;
  font-size: 0.9rem;
}

.quiz-option:hover { border-color: var(--terracotta); background: #FFF8F6; }

.quiz-option.selected { border-color: var(--navy); background: #F0F4FA; }

.quiz-option.correct {
  border-color: var(--green);
  background: var(--green-bg);
}

.quiz-option.incorrect {
  border-color: var(--red);
  background: var(--red-bg);
}

.quiz-option input[type="radio"] {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.quiz-option:focus-within {
  outline: 2px solid var(--terracotta);
  outline-offset: 2px;
}

.quiz-option .radio-dot {
  width: 20px;
  height: 20px;
  border: 2px solid #CBD5E0;
  border-radius: 50%;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s;
}

.quiz-option.selected .radio-dot {
  border-color: var(--navy);
  background: var(--navy);
}

.quiz-option.correct .radio-dot {
  border-color: var(--green);
  background: var(--green);
}

.quiz-option.incorrect .radio-dot {
  border-color: var(--red);
  background: var(--red);
}

.quiz-feedback {
  margin-top: 1rem;
  padding: 0.75rem 1rem;
  border-radius: 0.5rem;
  font-size: 0.9rem;
  display: none;
}

.quiz-feedback.correct {
  background: var(--green-bg);
  color: #276749;
  border: 1px solid #C6F6D5;
}

.quiz-feedback.incorrect {
  background: var(--red-bg);
  color: #9B2C2C;
  border: 1px solid #FED7D7;
}

.quiz-submit {
  margin-top: 1rem;
  background: var(--terracotta);
  color: white;
  border: none;
  padding: 0.6rem 1.5rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.875rem;
  cursor: pointer;
  transition: background 0.2s;
}

.quiz-submit:hover { background: var(--terracotta-dark); }
.quiz-submit:disabled { opacity: 0.5; cursor: not-allowed; }

/* --- Analogy Box --- */
.analogy-box {
  background: #FFFBF5;
  border-left: 3px solid var(--gold);
  padding: 1rem 1.25rem;
  border-radius: 0 0.5rem 0.5rem 0;
  margin: 1rem 0;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.analogy-box strong { color: var(--navy); }

/* --- Key Term --- */
.key-term {
  background: white;
  border: 1px solid #E2E8F0;
  border-radius: 0.5rem;
  padding: 1rem 1.25rem;
  margin: 0.75rem 0;
}

.key-term dt {
  font-weight: 700;
  color: var(--navy);
  font-size: 0.95rem;
}

.key-term dd {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-top: 0.25rem;
}

/* --- Lesson Progress Checkbox --- */
.lesson-complete-check {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  background: var(--warm-gray);
  padding: 1rem 1.25rem;
  border-radius: 0.75rem;
  margin: 2rem 0;
  cursor: pointer;
  transition: background 0.2s;
}

.lesson-complete-check:hover { background: #E8E4DE; }

.lesson-complete-check.locked {
  opacity: 0.6;
  cursor: not-allowed;
}

.lesson-complete-check.locked:hover { background: var(--warm-gray); }

.lesson-complete-check.locked input[type="checkbox"] { cursor: not-allowed; }

.lesson-complete-check input[type="checkbox"] {
  width: 22px;
  height: 22px;
  accent-color: var(--terracotta);
  cursor: pointer;
}

.lesson-complete-check span {
  font-weight: 600;
  color: var(--navy);
  font-size: 0.95rem;
}

/* --- Lesson Nav --- */
.lesson-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1.5rem 0;
  border-top: 1px solid #E2E8F0;
  margin-top: 2rem;
}

.lesson-nav a {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--navy);
  font-weight: 600;
  font-size: 0.9rem;
  text-decoration: none;
  transition: color 0.2s;
}

.lesson-nav a:hover { color: var(--terracotta); }

/* --- Buttons --- */
.btn-primary {
  background: var(--terracotta);
  color: white;
  transition: all 0.2s ease;
}
.btn-primary:hover { background: var(--terracotta-dark); }

/* --- Tag pill --- */
.tag-pill {
  display: inline-block;
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
  background: rgba(224, 122, 95, 0.1);
  color: var(--terracotta);
}

/* --- Skip to content --- */
.skip-to-content {
  position: absolute;
  top: -100%;
  left: 50%;
  transform: translateX(-50%);
  background: var(--terracotta);
  color: white;
  padding: 0.75rem 1.5rem;
  border-radius: 0 0 0.5rem 0.5rem;
  z-index: 100;
  transition: top 0.2s;
  font-weight: 600;
}
.skip-to-content:focus { top: 0; }

/* --- Focus styles --- */
a:focus-visible, button:focus-visible {
  outline: 2px solid var(--terracotta);
  outline-offset: 2px;
  border-radius: 2px;
}

/* --- Reduced motion --- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
  html { scroll-behavior: auto; }
}