:root {
  --ink: #14171C;
  --ink-soft: #1E232B;
  --charcoal: #262C36;
  --gold: #C08A2E;
  --gold-dark: #9C7024;
  --gold-bg: #FBF3E3;
  --gold-border: #E9D3A0;
  --bg-light: #F6F7F9;
  --border: #E1E4EA;
  --text-primary: #14171C;
  --text-secondary: #444B59;
  --text-muted: #838A99;
  --green: #1E7A54;
  --green-bg: #E7F4EE;
  --green-border: #BEE0CD;
  --red: #A83A32;
  --white: #FFFFFF;
}

* { box-sizing: border-box; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
  color: var(--text-primary);
  background: var(--white);
  margin: 0;
}

.container { max-width: 1140px; }

/* ---------- Sections ---------- */
.section-white { background: var(--white); padding: 5rem 0; }
.section-light { background: var(--bg-light); padding: 5rem 0; }
.section-ink { background: var(--ink); padding: 5rem 0; }

.section-label {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--gold-dark);
  display: block;
  margin-bottom: 0.6rem;
}
.section-title {
  font-size: clamp(1.6rem, 3.2vw, 2.4rem);
  font-weight: 800;
  color: var(--text-primary);
  line-height: 1.2;
}
.section-subtitle {
  font-size: 1rem;
  color: var(--text-secondary);
  max-width: 620px;
}

/* ---------- Navbar ---------- */
.md-navbar {
  background: var(--ink);
  padding: 0.9rem 0;
}
.md-navbar .navbar-brand {
  color: var(--white);
  font-weight: 800;
  font-size: 1.15rem;
  letter-spacing: -0.01em;
}
.md-navbar .navbar-brand span {
  display: block;
  font-size: 0.68rem;
  font-weight: 600;
  color: var(--gold);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-top: 1px;
}
.md-navbar .nav-link {
  color: rgba(255,255,255,0.75) !important;
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0.5rem 0.9rem !important;
}
.md-navbar .nav-link.active,
.md-navbar .nav-link:hover { color: var(--white) !important; }
.md-navbar .navbar-toggler { border-color: rgba(255,255,255,0.3); }
.md-navbar .navbar-toggler-icon {
  background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba(255,255,255,0.85)' stroke-width='2' stroke-linecap='round' stroke-miterlimit='10' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e");
}
.btn-nav-cta {
  background: var(--gold);
  color: var(--ink) !important;
  border-radius: 6px;
  padding: 0.5rem 1.1rem !important;
  font-weight: 700 !important;
}
.btn-nav-cta:hover { background: #D39B3E; }

/* ---------- Buttons ---------- */
.btn-md-primary {
  display: inline-block;
  background: var(--gold);
  color: var(--ink);
  font-weight: 700;
  font-size: 0.95rem;
  padding: 0.85rem 1.6rem;
  border-radius: 8px;
  border: 1.5px solid var(--gold);
  text-decoration: none;
  transition: all 0.15s ease;
}
.btn-md-primary:hover { background: #D39B3E; color: var(--ink); }
.btn-md-block { display: block; text-align: center; width: 100%; }

.btn-md-ghost {
  display: inline-block;
  background: transparent;
  color: var(--text-primary);
  font-weight: 700;
  font-size: 0.95rem;
  padding: 0.85rem 1.6rem;
  border-radius: 8px;
  border: 1.5px solid var(--border);
  text-decoration: none;
}
.btn-md-ghost:hover { border-color: var(--ink); }

.btn-md-primary-inverse {
  display: inline-block;
  background: var(--white);
  color: var(--ink);
  font-weight: 700;
  font-size: 0.95rem;
  padding: 0.85rem 1.6rem;
  border-radius: 8px;
  border: 1.5px solid var(--white);
  text-decoration: none;
}
.btn-md-primary-inverse:hover { background: var(--gold-bg); }

/* ---------- Cards ---------- */
.md-card {
  background: var(--white);
  border: 1.5px solid var(--border);
  border-radius: 12px;
  padding: 1.75rem;
}
.md-card-tinted {
  background: var(--bg-light);
  border: 1.5px solid var(--border);
  border-radius: 12px;
  padding: 1.75rem;
}

/* ---------- Badges / chips ---------- */
.badge-tag {
  display: inline-block;
  background: var(--gold-bg);
  border: 1.5px solid var(--gold-border);
  color: var(--gold-dark);
  font-size: 0.8rem;
  font-weight: 700;
  padding: 0.4rem 0.9rem;
  border-radius: 999px;
}
.ref-chip {
  display: inline-block;
  background: var(--white);
  border: 1.5px solid var(--border);
  color: var(--text-secondary);
  font-size: 0.82rem;
  font-weight: 600;
  padding: 0.5rem 1rem;
  border-radius: 999px;
  text-decoration: none;
  transition: all 0.15s ease;
}
a.ref-chip:hover {
  border-color: var(--gold);
  color: var(--gold-dark);
  background: var(--gold-bg);
}

.track-pill {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  padding: 0.3rem 0.7rem;
  border-radius: 999px;
}
.pill-critical { background: #FBEAE8; color: var(--red); border: 1px solid #F0C7C2; }
.pill-sharpen { background: var(--gold-bg); color: var(--gold-dark); border: 1px solid var(--gold-border); }
.pill-maintain { background: var(--green-bg); color: var(--green); border: 1px solid var(--green-border); }

/* ---------- Footer ---------- */
.md-footer {
  background: var(--ink);
  color: rgba(255,255,255,0.65);
  padding: 3.5rem 0 1.5rem;
}
.md-footer h5 {
  color: var(--white);
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 0.9rem;
}
.md-footer ul { list-style: none; padding: 0; margin: 0; }
.md-footer ul li { margin-bottom: 0.5rem; }
.md-footer a {
  color: rgba(255,255,255,0.6);
  text-decoration: none;
  font-size: 0.85rem;
}
.md-footer a:hover { color: var(--gold); }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.12);
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  font-size: 0.78rem;
  color: rgba(255,255,255,0.4);
}
.footer-bottom a { color: rgba(255,255,255,0.4); text-decoration: none; }
.footer-bottom a:hover { color: var(--gold); }

/* ---------- Accordion overrides ---------- */
.accordion-button:not(.collapsed) {
  color: var(--ink) !important;
  background: var(--gold-bg) !important;
}
.accordion-button:focus { box-shadow: none; border-color: var(--border); }

/* ---------- Quiz / interactive components ---------- */
.quiz-option {
  display: block;
  width: 100%;
  text-align: left;
  background: var(--white);
  border: 1.5px solid var(--border);
  border-radius: 8px;
  padding: 0.9rem 1.1rem;
  margin-bottom: 0.6rem;
  font-size: 0.9rem;
  color: var(--text-primary);
  cursor: pointer;
  transition: all 0.15s ease;
}
.quiz-option:hover { border-color: var(--gold); background: var(--gold-bg); }
.quiz-option.selected { border-color: var(--gold); background: var(--gold-bg); font-weight: 700; }
.quiz-option.correct { border-color: var(--green); background: var(--green-bg); font-weight: 700; }
.quiz-option.incorrect { border-color: var(--red); background: #FBEAE8; }
.quiz-option:disabled { cursor: default; }

.progress-track {
  height: 6px;
  background: var(--border);
  border-radius: 999px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: var(--gold);
  border-radius: 999px;
  transition: width 0.25s ease;
}

.gate-locked {
  opacity: 0.5;
  pointer-events: none;
}

.rubric-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.7rem 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.88rem;
}
.rubric-row:last-child { border-bottom: none; }

/* ---------- Focused single-step lesson viewer ---------- */
.step-shell {
  min-height: calc(100vh - 64px);
  display: flex;
  flex-direction: column;
}
.step-header {
  padding: 1.1rem 0 0.9rem;
}
.step-dots {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}
.step-dot {
  height: 6px;
  flex: 1;
  min-width: 14px;
  border-radius: 999px;
  background: var(--border);
}
.step-dot.done { background: var(--gold); }
.step-dot.current { background: var(--ink); }

.step-stage {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem 0;
}
.step-card {
  background: var(--white);
  border: 1.5px solid var(--border);
  border-radius: 14px;
  padding: 2.25rem;
  width: 100%;
  max-width: 680px;
  max-height: 62vh;
  overflow-y: auto;
}
.step-kicker {
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--gold-dark);
  margin-bottom: 0.6rem;
  display: block;
}
.step-footer {
  padding: 1.1rem 0 1.6rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-top: 1px solid var(--border);
}
.step-counter {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ---------- Resources bar (downloads) ---------- */
.resource-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  padding: 0.7rem 0 0;
}
.resource-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: var(--white);
  border: 1.5px solid var(--gold-border);
  color: var(--gold-dark);
  font-size: 0.78rem;
  font-weight: 700;
  padding: 0.4rem 0.8rem;
  border-radius: 8px;
  text-decoration: none;
}
.resource-btn:hover { background: var(--gold-bg); }

/* ---------- Worked example tables ---------- */
.example-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
  margin: 1rem 0;
}
.example-table th, .example-table td {
  border: 1px solid var(--border);
  padding: 0.55rem 0.7rem;
  text-align: right;
}
.example-table th:first-child, .example-table td:first-child { text-align: left; }
.example-table thead th {
  background: var(--ink);
  color: #fff;
  font-weight: 700;
}
.example-table tbody tr:nth-child(even) { background: var(--bg-light); }
.example-table tfoot td {
  font-weight: 800;
  background: var(--gold-bg);
  color: var(--ink);
}

/* ---------- Follow-up expandable box ---------- */
.followup-toggle {
  margin-top: 1rem;
  font-size: 0.83rem;
  font-weight: 700;
  color: var(--gold-dark);
  background: none;
  border: none;
  padding: 0;
  cursor: pointer;
  text-decoration: underline;
}
.followup-box {
  display: none;
  margin-top: 0.75rem;
  background: var(--ink);
  color: rgba(255,255,255,.85);
  border-radius: 8px;
  padding: 1rem 1.1rem;
  font-size: 0.85rem;
  line-height: 1.6;
}
.followup-box strong { color: var(--gold); }

/* ---------- Calc / build exercise inputs ---------- */
.calc-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.9rem;
  margin: 1.1rem 0;
}
.calc-field label {
  display: block;
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--text-secondary);
  margin-bottom: 0.3rem;
}
.calc-field input {
  width: 100%;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  padding: 0.55rem 0.7rem;
  font-size: 0.9rem;
}
.calc-output {
  margin-top: 1rem;
  background: var(--bg-light);
  border: 1.5px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  font-size: 0.9rem;
}
.calc-output .big-number {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--ink);
}
.calc-feedback {
  margin-top: 0.9rem;
  font-size: 0.85rem;
  font-weight: 700;
  padding: 0.7rem 0.9rem;
  border-radius: 8px;
}
.calc-feedback.correct { background: var(--green-bg); color: var(--green); border: 1px solid var(--green-border); }
.calc-feedback.incorrect { background: #FBEAE8; color: var(--red); border: 1px solid #F0C7C2; }