/* =============================================
   CAT MODELING ACADEMY — Design System
   Palette: deep navy, storm slate, risk amber, 
            signal teal, white
   ============================================= */

@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Sans:wght@300;400;500;600;700&family=IBM+Plex+Mono:wght@400;500&family=Playfair+Display:wght@700;900&display=swap');

:root {
  --navy:      #0B1F3A;
  --navy-mid:  #112952;
  --slate:     #2C4A6E;
  --slate-lt:  #4A708F;
  --teal:      #1B8F8A;
  --teal-lt:   #2BB8B2;
  --amber:     #E8A020;
  --amber-lt:  #F5C85A;
  --white:     #F6F8FB;
  --off-white: #EEF2F7;
  --text:      #1A2B3C;
  --text-muted:#5A7A9A;
  --border:    #D0DCE8;
  --success:   #2D9E6B;
  --danger:    #C0392B;

  --font-display: 'Playfair Display', Georgia, serif;
  --font-body:    'IBM Plex Sans', system-ui, sans-serif;
  --font-mono:    'IBM Plex Mono', monospace;

  --radius:  8px;
  --radius-lg: 16px;
  --shadow:  0 2px 12px rgba(11,31,58,0.10);
  --shadow-lg: 0 8px 32px rgba(11,31,58,0.16);
  --transition: 0.22s cubic-bezier(.4,0,.2,1);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; font-size: 16px; }

body {
  font-family: var(--font-body);
  color: var(--text);
  background: var(--white);
  line-height: 1.65;
}

/* ─── UTILITIES ─── */
.container { max-width: 1100px; margin: 0 auto; padding: 0 24px; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0,0,0,0); }
a { color: var(--teal); text-decoration: none; }
a:hover { color: var(--teal-lt); }
strong { font-weight: 600; }

/* ─── TOPBAR / NAV ─── */
#topbar {
  position: sticky; top: 0; z-index: 100;
  background: var(--navy);
  border-bottom: 2px solid var(--amber);
  padding: 0 24px;
}
.nav-inner {
  max-width: 1100px; margin: 0 auto;
  display: flex; align-items: center; gap: 16px;
  height: 58px;
}
.nav-logo {
  font-family: var(--font-display);
  font-size: 1.15rem;
  color: #fff;
  white-space: nowrap;
  flex-shrink: 0;
}
.nav-logo span { color: var(--amber); }
.nav-links {
  display: flex; gap: 4px; list-style: none;
  margin-left: auto; flex-wrap: wrap;
}
.nav-links a {
  color: rgba(255,255,255,0.75);
  font-size: 0.85rem; font-weight: 500;
  padding: 6px 12px; border-radius: var(--radius);
  transition: var(--transition);
}
.nav-links a:hover,
.nav-links a.active {
  background: rgba(255,255,255,0.1);
  color: #fff;
}
.nav-progress-bar {
  height: 3px; background: var(--slate);
  border-radius: 2px; overflow: hidden;
  width: 90px;
}
.nav-progress-fill {
  height: 100%; background: var(--teal-lt);
  transition: width 0.5s ease;
  width: 0%;
}

/* ─── HERO ─── */
.hero {
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy-mid) 60%, var(--slate) 100%);
  color: #fff;
  padding: 80px 24px 70px;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute; inset: 0;
  background-image: radial-gradient(circle at 70% 50%, rgba(27,143,138,0.18) 0%, transparent 60%),
                    radial-gradient(circle at 20% 80%, rgba(232,160,32,0.10) 0%, transparent 50%);
}
.hero-inner { max-width: 1100px; margin: 0 auto; position: relative; }
.hero-eyebrow {
  font-family: var(--font-mono);
  font-size: 0.78rem; letter-spacing: 0.14em;
  text-transform: uppercase; color: var(--amber);
  margin-bottom: 18px;
}
.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(2.2rem, 5vw, 3.6rem);
  line-height: 1.12;
  margin-bottom: 20px;
  max-width: 700px;
}
.hero h1 em { color: var(--teal-lt); font-style: normal; }
.hero-sub {
  font-size: 1.1rem; color: rgba(255,255,255,0.78);
  max-width: 540px; margin-bottom: 36px;
  line-height: 1.7;
}
.hero-cta {
  display: inline-flex; align-items: center; gap: 10px;
  background: var(--amber); color: var(--navy);
  font-weight: 700; font-size: 0.95rem;
  padding: 14px 28px; border-radius: var(--radius);
  transition: var(--transition);
  box-shadow: 0 4px 16px rgba(232,160,32,0.35);
}
.hero-cta:hover { background: var(--amber-lt); color: var(--navy); transform: translateY(-2px); }
.hero-stats {
  display: flex; gap: 40px; margin-top: 56px;
  flex-wrap: wrap;
}
.hero-stat-val {
  font-family: var(--font-display);
  font-size: 2rem; font-weight: 900; color: var(--teal-lt);
}
.hero-stat-lbl {
  font-size: 0.8rem; color: rgba(255,255,255,0.55);
  font-family: var(--font-mono); letter-spacing: 0.06em;
  text-transform: uppercase;
}

/* ─── SECTION HEADINGS ─── */
.section-label {
  font-family: var(--font-mono);
  font-size: 0.72rem; letter-spacing: 0.16em;
  text-transform: uppercase; color: var(--teal);
  margin-bottom: 10px;
}
.section-title {
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  color: var(--navy);
  margin-bottom: 12px;
}
.section-subtitle {
  color: var(--text-muted); font-size: 1rem;
  max-width: 560px;
}

/* ─── COURSE MODULES GRID ─── */
#modules { padding: 80px 24px; background: var(--off-white); }
.modules-header { margin-bottom: 44px; }
.modules-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
}
.module-card {
  background: #fff;
  border-radius: var(--radius-lg);
  border: 1.5px solid var(--border);
  padding: 28px;
  transition: var(--transition);
  cursor: pointer;
  position: relative;
  overflow: hidden;
}
.module-card::before {
  content: '';
  position: absolute; top: 0; left: 0; right: 0;
  height: 4px;
  background: var(--teal);
  transform: scaleX(0); transform-origin: left;
  transition: transform var(--transition);
}
.module-card:hover { box-shadow: var(--shadow-lg); transform: translateY(-3px); border-color: var(--teal); }
.module-card:hover::before { transform: scaleX(1); }
.module-num {
  font-family: var(--font-mono);
  font-size: 0.72rem; color: var(--text-muted);
  letter-spacing: 0.1em; margin-bottom: 12px;
}
.module-icon {
  width: 44px; height: 44px;
  background: linear-gradient(135deg, var(--navy), var(--slate));
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.3rem; margin-bottom: 14px;
}
.module-card h3 {
  font-size: 1.05rem; font-weight: 600;
  color: var(--navy); margin-bottom: 8px;
}
.module-card p {
  font-size: 0.875rem; color: var(--text-muted);
  line-height: 1.6; margin-bottom: 18px;
}
.module-meta {
  display: flex; gap: 14px; align-items: center;
}
.module-tag {
  font-size: 0.72rem; font-weight: 600;
  padding: 3px 10px; border-radius: 20px;
  background: var(--off-white); color: var(--slate);
  font-family: var(--font-mono);
}
.module-lessons { font-size: 0.8rem; color: var(--text-muted); }
.module-status {
  margin-left: auto;
  width: 22px; height: 22px;
  border-radius: 50%; border: 2px solid var(--border);
  display: flex; align-items: center; justify-content: center;
  font-size: 0.65rem; color: var(--text-muted);
}
.module-status.done { background: var(--success); border-color: var(--success); color: #fff; }

/* ─── HOW IT WORKS ─── */
#how-it-works { padding: 80px 24px; background: #fff; }
.how-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 32px; margin-top: 44px;
}
.how-step {
  display: flex; flex-direction: column; gap: 12px;
}
.how-step-num {
  font-family: var(--font-display);
  font-size: 3rem; font-weight: 900;
  color: var(--border); line-height: 1;
}
.how-step h4 { font-size: 1rem; font-weight: 600; color: var(--navy); }
.how-step p { font-size: 0.875rem; color: var(--text-muted); line-height: 1.65; }

/* ─── LESSON PAGE ─── */
.lesson-layout {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 0;
  min-height: calc(100vh - 58px);
}

/* SIDEBAR */
.sidebar {
  background: var(--navy);
  color: #fff;
  padding: 28px 0;
  position: sticky; top: 58px;
  height: calc(100vh - 58px);
  overflow-y: auto;
}
.sidebar-module-title {
  font-size: 0.7rem; letter-spacing: 0.12em;
  text-transform: uppercase; color: var(--amber);
  font-family: var(--font-mono);
  padding: 0 20px; margin-bottom: 16px;
}
.sidebar-nav { list-style: none; }
.sidebar-nav li a {
  display: flex; align-items: center; gap: 10px;
  padding: 10px 20px;
  font-size: 0.875rem; color: rgba(255,255,255,0.65);
  transition: var(--transition);
  border-left: 3px solid transparent;
}
.sidebar-nav li a:hover { color: #fff; background: rgba(255,255,255,0.07); }
.sidebar-nav li a.active { color: var(--teal-lt); border-left-color: var(--teal-lt); background: rgba(43,184,178,0.08); }
.sidebar-nav li a.completed { color: rgba(255,255,255,0.45); }
.sidebar-nav li a.completed .lesson-check { color: var(--success); }
.lesson-check { font-size: 0.9rem; flex-shrink: 0; }
.sidebar-divider {
  height: 1px; background: rgba(255,255,255,0.08);
  margin: 16px 20px;
}

/* LESSON CONTENT */
.lesson-content {
  padding: 48px 56px;
  max-width: 820px;
}
.lesson-breadcrumb {
  font-size: 0.78rem; color: var(--text-muted);
  font-family: var(--font-mono);
  margin-bottom: 28px; display: flex; gap: 8px; align-items: center;
}
.lesson-breadcrumb span { color: var(--border); }
.lesson-header { margin-bottom: 36px; }
.lesson-header .lesson-tag {
  display: inline-block;
  font-family: var(--font-mono); font-size: 0.72rem;
  padding: 4px 12px; border-radius: 20px;
  background: rgba(27,143,138,0.12); color: var(--teal);
  margin-bottom: 14px; font-weight: 500;
}
.lesson-header h1 {
  font-family: var(--font-display);
  font-size: 2rem; color: var(--navy);
  margin-bottom: 10px; line-height: 1.25;
}
.lesson-header .lesson-meta {
  font-size: 0.82rem; color: var(--text-muted);
  display: flex; gap: 16px; flex-wrap: wrap;
}
.lesson-body { line-height: 1.8; }
.lesson-body h2 {
  font-family: var(--font-display);
  font-size: 1.4rem; color: var(--navy);
  margin: 40px 0 14px;
  padding-bottom: 8px;
  border-bottom: 1.5px solid var(--border);
}
.lesson-body h3 {
  font-size: 1.05rem; font-weight: 600;
  color: var(--slate); margin: 28px 0 10px;
}
.lesson-body p { margin-bottom: 18px; }
.lesson-body ul, .lesson-body ol {
  padding-left: 22px; margin-bottom: 18px;
}
.lesson-body li { margin-bottom: 7px; }

/* Callout boxes */
.callout {
  border-radius: var(--radius);
  padding: 18px 20px;
  margin: 28px 0;
  border-left: 4px solid;
  font-size: 0.9rem;
}
.callout.info { background: rgba(27,143,138,0.07); border-color: var(--teal); }
.callout.warning { background: rgba(232,160,32,0.08); border-color: var(--amber); }
.callout.key { background: rgba(11,31,58,0.05); border-color: var(--navy-mid); }
.callout-label {
  font-family: var(--font-mono);
  font-size: 0.7rem; letter-spacing: 0.1em;
  text-transform: uppercase; font-weight: 600;
  margin-bottom: 6px;
}
.callout.info .callout-label { color: var(--teal); }
.callout.warning .callout-label { color: var(--amber); }
.callout.key .callout-label { color: var(--navy); }

/* Definition terms */
.term {
  font-family: var(--font-mono);
  font-size: 0.9em; font-weight: 500;
  background: rgba(27,143,138,0.09);
  color: var(--teal);
  padding: 2px 7px; border-radius: 4px;
}

/* ─── QUIZ ─── */
.quiz-section {
  background: var(--off-white);
  border-radius: var(--radius-lg);
  padding: 32px;
  margin: 40px 0;
  border: 1.5px solid var(--border);
}
.quiz-header { margin-bottom: 28px; }
.quiz-header h2 {
  font-family: var(--font-display);
  font-size: 1.4rem; color: var(--navy);
  margin-bottom: 4px; border: none; padding: 0;
}
.quiz-header p { font-size: 0.875rem; color: var(--text-muted); }
.quiz-question { margin-bottom: 28px; }
.quiz-question h4 {
  font-size: 0.95rem; font-weight: 600;
  color: var(--navy); margin-bottom: 14px;
  line-height: 1.5;
}
.quiz-options { display: flex; flex-direction: column; gap: 8px; }
.quiz-option {
  display: flex; align-items: flex-start; gap: 12px;
  padding: 12px 16px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer; background: #fff;
  transition: var(--transition);
  font-size: 0.9rem; color: var(--text);
}
.quiz-option:hover { border-color: var(--teal); background: rgba(27,143,138,0.04); }
.quiz-option.selected { border-color: var(--teal); background: rgba(27,143,138,0.08); }
.quiz-option.correct { border-color: var(--success); background: rgba(45,158,107,0.08); color: var(--success); }
.quiz-option.incorrect { border-color: var(--danger); background: rgba(192,57,43,0.06); color: var(--danger); }
.option-letter {
  width: 24px; height: 24px; flex-shrink: 0;
  border-radius: 50%; border: 1.5px solid var(--border);
  display: flex; align-items: center; justify-content: center;
  font-family: var(--font-mono); font-size: 0.75rem; font-weight: 600;
  color: var(--text-muted);
}
.quiz-option.selected .option-letter { border-color: var(--teal); color: var(--teal); }
.quiz-option.correct .option-letter { border-color: var(--success); background: var(--success); color: #fff; }
.quiz-option.incorrect .option-letter { border-color: var(--danger); background: var(--danger); color: #fff; }
.quiz-submit {
  background: var(--navy); color: #fff;
  border: none; cursor: pointer;
  font-family: var(--font-body); font-size: 0.9rem; font-weight: 600;
  padding: 12px 28px; border-radius: var(--radius);
  transition: var(--transition); margin-top: 8px;
}
.quiz-submit:hover { background: var(--slate); }
.quiz-submit:disabled { opacity: 0.5; cursor: not-allowed; }
.quiz-feedback {
  margin-top: 18px; padding: 16px 18px;
  border-radius: var(--radius); font-size: 0.875rem;
  display: none;
}
.quiz-feedback.show { display: block; }
.quiz-feedback.pass { background: rgba(45,158,107,0.1); color: #1d6b48; border: 1px solid rgba(45,158,107,0.25); }
.quiz-feedback.fail { background: rgba(192,57,43,0.08); color: #8b2a1d; border: 1px solid rgba(192,57,43,0.2); }
.quiz-score { font-weight: 700; font-size: 1.1rem; }

/* ─── LESSON NAV FOOTER ─── */
.lesson-nav-footer {
  display: flex; justify-content: space-between; align-items: center;
  margin-top: 56px; padding-top: 24px;
  border-top: 1.5px solid var(--border);
  flex-wrap: wrap; gap: 12px;
}
.lesson-nav-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 11px 22px; border-radius: var(--radius);
  font-size: 0.875rem; font-weight: 600;
  transition: var(--transition); cursor: pointer;
  border: 1.5px solid;
}
.lesson-nav-btn.prev { border-color: var(--border); color: var(--text-muted); background: #fff; }
.lesson-nav-btn.prev:hover { border-color: var(--slate); color: var(--navy); }
.lesson-nav-btn.next { border-color: var(--teal); color: #fff; background: var(--teal); }
.lesson-nav-btn.next:hover { background: var(--teal-lt); border-color: var(--teal-lt); }
.mark-complete-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 10px 20px; border-radius: var(--radius);
  font-size: 0.875rem; font-weight: 600;
  border: 1.5px solid var(--success); color: var(--success);
  background: transparent; cursor: pointer;
  transition: var(--transition);
}
.mark-complete-btn:hover, .mark-complete-btn.done {
  background: var(--success); color: #fff;
}

/* ─── GLOSSARY ─── */
.glossary-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px; margin-top: 32px;
}
.glossary-card {
  background: #fff; border: 1.5px solid var(--border);
  border-radius: var(--radius); padding: 18px 20px;
}
.glossary-card dt {
  font-family: var(--font-mono); font-size: 0.85rem; font-weight: 600;
  color: var(--teal); margin-bottom: 6px;
}
.glossary-card dd {
  font-size: 0.875rem; color: var(--text-muted); line-height: 1.6;
}

/* ─── PROGRESS DASHBOARD ─── */
.progress-panel {
  background: var(--navy);
  color: #fff;
  border-radius: var(--radius-lg);
  padding: 28px 32px;
  margin: 32px 0;
}
.progress-panel h3 {
  font-family: var(--font-display);
  font-size: 1.15rem; margin-bottom: 20px;
}
.progress-modules { display: flex; flex-direction: column; gap: 12px; }
.progress-row {
  display: flex; align-items: center; gap: 14px;
}
.progress-row-label {
  font-size: 0.8rem; color: rgba(255,255,255,0.65);
  min-width: 160px;
}
.progress-bar {
  flex: 1; height: 6px; background: rgba(255,255,255,0.12);
  border-radius: 3px; overflow: hidden;
}
.progress-bar-fill {
  height: 100%; background: var(--teal-lt);
  border-radius: 3px; transition: width 0.8s ease;
}
.progress-pct {
  font-family: var(--font-mono); font-size: 0.78rem;
  color: var(--teal-lt); min-width: 34px; text-align: right;
}

/* ─── FOOTER ─── */
footer {
  background: var(--navy); color: rgba(255,255,255,0.5);
  padding: 32px 24px; text-align: center;
  font-size: 0.82rem;
}
footer strong { color: rgba(255,255,255,0.8); }

/* ─── RESPONSIVE ─── */
@media (max-width: 768px) {
  .lesson-layout { grid-template-columns: 1fr; }
  .sidebar {
    position: static; height: auto;
    padding: 20px 0;
  }
  .lesson-content { padding: 28px 20px; }
  .hero { padding: 52px 20px 48px; }
  .hero-stats { gap: 28px; }
  .nav-links { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
}