:root {
  --bg-primary: #0b1020;
  --bg-secondary: #121a30;
  --bg-card: #16203a;
  --bg-card-hover: #1d2a4a;
  --bg-canvas: #080d1a;
  --border-subtle: #26355c;
  --border-highlight: #3b82f6;

  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  /* AWS Concept Color Coding */
  --aws-orange: #ff9900;
  --aws-orange-soft: rgba(255, 153, 0, 0.14);
  --vpc-green: #10b981;
  --vpc-green-soft: rgba(16, 185, 129, 0.12);
  --public-blue: #38bdf8;
  --public-blue-soft: rgba(56, 189, 248, 0.12);
  --private-indigo: #818cf8;
  --private-indigo-soft: rgba(129, 140, 248, 0.12);
  --sg-amber: #f59e0b;
  --sg-amber-soft: rgba(245, 158, 11, 0.14);
  --nacl-cyan: #06b6d4;
  --nacl-cyan-soft: rgba(6, 182, 212, 0.14);
  --endpoint-purple: #c084fc;
  --endpoint-purple-soft: rgba(192, 132, 252, 0.14);
  --org-rose: #f43f5e;
  --org-rose-soft: rgba(244, 63, 94, 0.14);
  --success: #22c55e;
  --danger: #ef4444;
  --warning: #eab308;

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --shadow-card: 0 10px 25px -5px rgba(0, 0, 0, 0.45);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.55;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
}

/* Top Navigation Bar */
.top-navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(11, 16, 32, 0.94);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-subtle);
  padding: 0.6rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.navbar-top-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  width: auto;
}

.brand-group {
  display: flex;
  align-items: center;
  gap: 0.65rem;
}

.brand-logo {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--aws-orange), #f97316);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  color: #0b1020;
  font-size: 0.98rem;
  flex-shrink: 0;
  box-shadow: 0 4px 12px rgba(255, 153, 0, 0.3);
}

.brand-title {
  font-weight: 700;
  font-size: 1rem;
  letter-spacing: -0.01em;
  display: flex;
  flex-direction: column;
}

.brand-subtitle {
  font-size: 0.72rem;
  color: var(--text-secondary);
  font-weight: 400;
}

.mobile-menu-toggle {
  display: none;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  border-radius: var(--radius-sm);
  padding: 0.42rem 0.7rem;
  font-size: 0.78rem;
  font-weight: 700;
  cursor: pointer;
  align-items: center;
  gap: 0.35rem;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  flex-wrap: wrap;
}

.nav-link {
  padding: 0.44rem 0.76rem;
  border-radius: var(--radius-sm);
  font-size: 0.81rem;
  font-weight: 500;
  color: var(--text-secondary);
  border: 1px solid transparent;
  transition: all 0.18s ease;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  white-space: nowrap;
}

.nav-link:hover {
  color: var(--text-primary);
  background: var(--bg-secondary);
  border-color: var(--border-subtle);
}

.nav-link.active {
  color: #fff;
  background: rgba(59, 130, 246, 0.2);
  border-color: var(--border-highlight);
  font-weight: 600;
}

.nav-step-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 19px;
  height: 19px;
  border-radius: 50%;
  font-size: 0.68rem;
  font-weight: 700;
  background: rgba(255, 255, 255, 0.1);
  flex-shrink: 0;
}

.nav-link.active .nav-step-badge {
  background: var(--border-highlight);
  color: #fff;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.55rem;
}

/* Mode switcher: Plain English vs Technical */
.explain-mode-switch {
  display: inline-flex;
  background: var(--bg-secondary);
  border: 1px solid var(--border-subtle);
  border-radius: 999px;
  padding: 2px;
}

.explain-mode-btn {
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.74rem;
  font-weight: 600;
  padding: 0.32rem 0.7rem;
  border-radius: 999px;
  cursor: pointer;
  transition: all 0.15s ease;
  white-space: nowrap;
}

.explain-mode-btn.active {
  background: var(--aws-orange);
  color: #0b1020;
}

.btn-glossary {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  font-size: 0.76rem;
  font-weight: 600;
  padding: 0.4rem 0.75rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  transition: all 0.15s ease;
  white-space: nowrap;
}

.btn-glossary:hover {
  border-color: var(--aws-orange);
  background: var(--bg-card-hover);
}

/* Main Page Container */
.page-container {
  max-width: 1560px;
  width: 100%;
  margin: 0 auto;
  padding: 1.25rem 1.5rem 3.5rem;
  flex: 1;
}

/* Page Header Banner */
.module-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1.25rem;
  margin-bottom: 1.25rem;
  padding: 1.15rem 1.4rem;
  background: linear-gradient(135deg, rgba(22, 32, 58, 0.9), rgba(18, 26, 48, 0.9));
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  flex-wrap: wrap;
}

.module-header-left {
  max-width: 880px;
  flex: 1 1 540px;
}

.module-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  font-size: 0.74rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 700;
  color: var(--aws-orange);
  margin-bottom: 0.35rem;
}

.module-title {
  font-size: 1.55rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 0.4rem;
  line-height: 1.25;
}

.module-intro {
  color: var(--text-secondary);
  font-size: 0.92rem;
}

/* Analogy Callout Box */
.analogy-banner {
  background: rgba(255, 153, 0, 0.08);
  border: 1px solid rgba(255, 153, 0, 0.35);
  border-radius: var(--radius-md);
  padding: 0.85rem 1.1rem;
  margin-top: 0.75rem;
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
}

.analogy-icon {
  font-size: 1.35rem;
  line-height: 1;
  margin-top: 0.1rem;
  flex-shrink: 0;
}

.analogy-text {
  font-size: 0.86rem;
  color: #fde68a;
}

.analogy-text strong {
  color: #fff;
}

/* Hide/show based on global explain mode */
body[data-explain-mode="technical"] .analogy-only {
  display: none !important;
}

body[data-explain-mode="beginner"] .technical-only {
  display: none !important;
}

/* Interactive Workspace Split Grid */
.workspace-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.65fr) minmax(350px, 1fr);
  gap: 1.25rem;
  align-items: start;
}

/* Diagram Canvas Card */
.canvas-card {
  background: var(--bg-canvas);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.canvas-toolbar {
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-subtle);
  padding: 0.75rem 1.1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.canvas-toolbar-title {
  font-size: 0.88rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.status-dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--success);
  box-shadow: 0 0 8px var(--success);
  flex-shrink: 0;
}

.toolbar-controls {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}

/* Mobile Zoom & Auto-Follow Bar inside Canvas */
.canvas-zoom-bar {
  background: rgba(15, 23, 42, 0.9);
  border-bottom: 1px solid rgba(255, 255, 255, 0.07);
  padding: 0.42rem 0.85rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  flex-wrap: wrap;
  font-size: 0.74rem;
  color: var(--text-secondary);
}

.zoom-btn-group {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  flex-wrap: wrap;
}

.zoom-chip {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  font-size: 0.72rem;
  font-weight: 600;
  padding: 0.26rem 0.58rem;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.14s ease;
}

.zoom-chip:hover {
  border-color: var(--border-highlight);
}

.zoom-chip.active {
  background: rgba(59, 130, 246, 0.24);
  border-color: var(--border-highlight);
  color: #fff;
}

.svg-stage-wrapper {
  position: relative;
  width: 100%;
  overflow-x: auto;
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
  overscroll-behavior-x: contain;
  background:
    radial-gradient(circle at 20% 20%, rgba(56, 189, 248, 0.05), transparent 45%),
    radial-gradient(circle at 80% 75%, rgba(16, 185, 129, 0.05), transparent 45%),
    linear-gradient(rgba(38, 53, 92, 0.18) 1px, transparent 1px),
    linear-gradient(90deg, rgba(38, 53, 92, 0.18) 1px, transparent 1px);
  background-size: 100% 100%, 100% 100%, 28px 28px, 28px 28px;
  padding: 0.5rem;
}

.network-svg {
  width: 100%;
  height: auto;
  display: block;
  user-select: none;
  transition: width 0.2s ease, min-width 0.2s ease;
}

/* Zoom levels applied to .svg-stage-wrapper */
.svg-stage-wrapper[data-zoom="1.4"] .network-svg {
  min-width: 780px;
}

.svg-stage-wrapper[data-zoom="1.8"] .network-svg {
  min-width: 1020px;
}

/* Mobile Live Step HUD Banner directly below the diagram */
.mobile-live-hud {
  background: linear-gradient(90deg, rgba(15, 23, 42, 0.96), rgba(22, 32, 58, 0.96));
  border-top: 1px solid var(--border-subtle);
  padding: 0.6rem 0.95rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  font-size: 0.79rem;
}

.mobile-hud-text {
  display: flex;
  flex-direction: column;
  gap: 0.12rem;
  min-width: 0;
  flex: 1;
}

.mobile-hud-title {
  font-weight: 700;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 0.45rem;
  flex-wrap: wrap;
}

.mobile-hud-desc {
  color: var(--text-secondary);
  font-size: 0.74rem;
}

/* SVG Interactive Elements */
.svg-clickable {
  cursor: pointer;
  transition: filter 0.18s ease, opacity 0.18s ease;
}

.svg-clickable:hover {
  filter: brightness(1.18) drop-shadow(0 0 8px rgba(59, 130, 246, 0.45));
}

.svg-clickable.selected-node {
  filter: drop-shadow(0 0 10px rgba(255, 153, 0, 0.75));
}

.flow-path {
  fill: none;
  stroke-width: 3;
  stroke-linecap: round;
  stroke-dasharray: 8 6;
  animation: dashFlow 1.2s linear infinite;
}

@keyframes dashFlow {
  to {
    stroke-dashoffset: -28;
  }
}

.packet-orb {
  filter: drop-shadow(0 0 8px currentColor);
  transition: all 0.08s linear;
}

/* Legend Bar at Bottom of Canvas */
.canvas-legend {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-subtle);
  padding: 0.6rem 1.1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  flex-wrap: wrap;
  font-size: 0.76rem;
  color: var(--text-secondary);
}

.legend-items {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  flex-wrap: wrap;
}

.legend-item {
  display: inline-flex;
  align-items: center;
  gap: 0.38rem;
}

.legend-swatch {
  width: 11px;
  height: 11px;
  border-radius: 3px;
  display: inline-block;
  flex-shrink: 0;
}

/* Right Side Inspector & Control Panels */
.side-panel {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  min-width: 0;
}

.panel-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 1.1rem 1.2rem;
  box-shadow: var(--shadow-card);
  overflow-x: auto;
}

.panel-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  margin-bottom: 0.8rem;
  padding-bottom: 0.6rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.07);
  flex-wrap: wrap;
}

.panel-card-title {
  font-size: 0.94rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 0.45rem;
}

.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.18rem 0.55rem;
  border-radius: 999px;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.badge-green {
  background: rgba(34, 197, 94, 0.16);
  color: #4ade80;
  border: 1px solid rgba(34, 197, 94, 0.35);
}

.badge-red {
  background: rgba(239, 68, 68, 0.16);
  color: #f87171;
  border: 1px solid rgba(239, 68, 68, 0.35);
}

.badge-amber {
  background: rgba(245, 158, 11, 0.16);
  color: #fbbf24;
  border: 1px solid rgba(245, 158, 11, 0.35);
}

.badge-blue {
  background: rgba(56, 189, 248, 0.16);
  color: #38bdf8;
  border: 1px solid rgba(56, 189, 248, 0.35);
}

.badge-purple {
  background: rgba(192, 132, 252, 0.16);
  color: #c084fc;
  border: 1px solid rgba(192, 132, 252, 0.35);
}

/* Interactive Buttons */
.btn {
  border: 1px solid var(--border-subtle);
  background: var(--bg-secondary);
  color: var(--text-primary);
  padding: 0.52rem 0.85rem;
  min-height: 38px;
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  transition: all 0.16s ease;
  text-align: center;
}

.btn:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-highlight);
}

.btn-primary {
  background: linear-gradient(135deg, #2563eb, #1d4ed8);
  border-color: #3b82f6;
  color: #fff;
}

.btn-primary:hover {
  background: linear-gradient(135deg, #3b82f6, #2563eb);
  box-shadow: 0 0 14px rgba(59, 130, 246, 0.4);
}

.btn-orange {
  background: linear-gradient(135deg, #ff9900, #ea580c);
  border-color: #ff9900;
  color: #0b1020;
  font-weight: 700;
}

.btn-orange:hover {
  filter: brightness(1.08);
  box-shadow: 0 0 14px rgba(255, 153, 0, 0.4);
}

.btn-success {
  background: rgba(34, 197, 94, 0.18);
  border-color: #22c55e;
  color: #4ade80;
}

.btn-danger {
  background: rgba(239, 68, 68, 0.18);
  border-color: #ef4444;
  color: #f87171;
}

.btn-group-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 0.5rem;
}

/* Toggle Switches for Network Controls */
.control-list {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.control-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.65rem 0.78rem;
  background: rgba(11, 16, 32, 0.55);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
}

.control-label {
  font-size: 0.81rem;
  font-weight: 600;
}

.control-sublabel {
  font-size: 0.72rem;
  color: var(--text-secondary);
  display: block;
  margin-top: 0.12rem;
}

/* Toggle Switch UI */
.toggle-switch {
  position: relative;
  width: 44px;
  height: 24px;
  flex-shrink: 0;
}

.toggle-switch input {
  opacity: 0;
  width: 0;
  height: 0;
}

.toggle-slider {
  position: absolute;
  cursor: pointer;
  inset: 0;
  background-color: #334155;
  transition: 0.2s;
  border-radius: 999px;
}

.toggle-slider:before {
  position: absolute;
  content: "";
  height: 18px;
  width: 18px;
  left: 3px;
  bottom: 3px;
  background-color: white;
  transition: 0.2s;
  border-radius: 50%;
}

.toggle-switch input:checked + .toggle-slider {
  background-color: var(--success);
}

.toggle-switch input:checked + .toggle-slider:before {
  transform: translateX(20px);
}

/* Packet Log / Step Trace Box */
.trace-log {
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
  max-height: 290px;
  overflow-y: auto;
  padding-right: 0.2rem;
}

.trace-step {
  padding: 0.55rem 0.7rem;
  border-radius: var(--radius-sm);
  font-size: 0.79rem;
  background: rgba(11, 16, 32, 0.65);
  border-left: 3px solid var(--border-highlight);
  display: flex;
  flex-direction: column;
  gap: 0.18rem;
}

.trace-step.pass {
  border-left-color: var(--success);
  background: rgba(34, 197, 94, 0.08);
}

.trace-step.block {
  border-left-color: var(--danger);
  background: rgba(239, 68, 68, 0.11);
}

.trace-step.rewrite {
  border-left-color: var(--aws-orange);
  background: rgba(255, 153, 0, 0.1);
}

.trace-step-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.4rem;
  font-weight: 700;
  flex-wrap: wrap;
}

.trace-step-desc {
  color: var(--text-secondary);
  font-size: 0.75rem;
}

/* Mini Data Tables (Route Tables, NAT State, SG Rules) */
.mini-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.76rem;
}

.mini-table th,
.mini-table td {
  padding: 0.44rem 0.55rem;
  text-align: left;
  border-bottom: 1px solid rgba(255, 255, 255, 0.07);
}

.mini-table th {
  color: var(--text-secondary);
  font-weight: 600;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.code-pill {
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  font-size: 0.72rem;
  background: rgba(15, 23, 42, 0.85);
  padding: 0.12rem 0.4rem;
  border-radius: 4px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: #e2e8f0;
  word-break: break-word;
}

/* Tabs Bar */
.sub-tabs {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

.sub-tab-btn {
  padding: 0.58rem 0.95rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-subtle);
  background: var(--bg-secondary);
  color: var(--text-secondary);
  font-weight: 600;
  font-size: 0.82rem;
  cursor: pointer;
  transition: all 0.16s ease;
  text-align: left;
}

.sub-tab-btn:hover {
  color: var(--text-primary);
  border-color: var(--border-highlight);
}

.sub-tab-btn.active {
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.25), rgba(37, 99, 235, 0.15));
  color: #fff;
  border-color: var(--border-highlight);
}

/* Module Footer Navigation (Prev / Next Page) */
.module-footer-nav {
  margin-top: 2rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  flex-wrap: wrap;
}

/* Cards Grid for Overview & Key Takeaways */
.cards-grid-3 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
  margin-top: 1.25rem;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1.1rem 1.2rem;
  transition: transform 0.16s ease, border-color 0.16s ease;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 0.75rem;
}

.feature-card:hover {
  transform: translateY(-2px);
  border-color: var(--border-highlight);
}

/* Glossary Modal */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(4, 7, 17, 0.78);
  backdrop-filter: blur(6px);
  z-index: 200;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 1.25rem;
}

.modal-backdrop.open {
  display: flex;
}

.modal-content {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  max-width: 880px;
  width: 100%;
  max-height: 86vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.75);
}

.modal-header {
  padding: 0.95rem 1.25rem;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
}

.modal-body {
  padding: 1.15rem 1.25rem;
  overflow-y: auto;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 0.85rem;
}

.glossary-item {
  background: rgba(11, 16, 32, 0.6);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 0.75rem 0.85rem;
}

.glossary-term {
  font-weight: 700;
  font-size: 0.86rem;
  color: var(--aws-orange);
  margin-bottom: 0.25rem;
}

.glossary-analogy {
  font-size: 0.76rem;
  color: #fde68a;
  margin-bottom: 0.25rem;
}

.glossary-def {
  font-size: 0.76rem;
  color: var(--text-secondary);
}

/* =====================================================================
   MOBILE & TABLET RESPONSIVE DESIGN
   ===================================================================== */

@media (max-width: 1120px) {
  .workspace-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 900px) {
  .top-navbar {
    padding: 0.55rem 0.85rem;
    gap: 0.5rem;
  }

  .navbar-top-row {
    width: 100%;
  }

  .mobile-menu-toggle {
    display: inline-flex;
  }

  /* Horizontal swipeable module pill bar by default on mobile; expands to grid when menu toggled */
  .nav-links {
    width: 100%;
    flex-wrap: nowrap;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
    padding-bottom: 2px;
    order: 3;
  }

  .nav-links::-webkit-scrollbar {
    display: none;
  }

  .nav-links.mobile-expanded {
    flex-wrap: wrap;
    overflow-x: visible;
    background: var(--bg-secondary);
    padding: 0.5rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-subtle);
  }

  .nav-links.mobile-expanded .nav-link {
    flex: 1 1 calc(50% - 0.35rem);
  }

  .nav-actions {
    width: 100%;
    justify-content: space-between;
    order: 2;
  }
}

@media (max-width: 640px) {
  .page-container {
    padding: 0.75rem 0.75rem 3rem;
  }

  .brand-subtitle {
    display: none;
  }

  .module-header {
    padding: 0.9rem 1rem;
    gap: 0.9rem;
    margin-bottom: 0.9rem;
  }

  .module-title {
    font-size: 1.22rem;
  }

  .module-intro {
    font-size: 0.84rem;
  }

  .analogy-banner {
    padding: 0.7rem 0.85rem;
    gap: 0.55rem;
  }

  .analogy-text {
    font-size: 0.8rem;
  }

  /* Full-width header CTA buttons on mobile */
  .module-header > div:last-child {
    width: 100%;
  }

  .module-header > div:last-child .btn {
    width: 100%;
  }

  /* Sub-tabs scroll horizontally or stack cleanly on phone screens */
  .sub-tabs {
    flex-direction: column;
    gap: 0.4rem;
  }

  .sub-tab-btn {
    width: 100%;
    font-size: 0.79rem;
    padding: 0.6rem 0.8rem;
  }

  .canvas-toolbar {
    padding: 0.65rem 0.8rem;
    flex-direction: column;
    align-items: stretch;
  }

  .toolbar-controls {
    display: grid;
    grid-template-columns: 1fr;
    gap: 0.42rem;
    width: 100%;
  }

  .toolbar-controls .btn {
    width: 100%;
    justify-content: flex-start;
    padding: 0.55rem 0.75rem;
    font-size: 0.78rem;
  }

  .panel-card {
    padding: 0.9rem 0.95rem;
  }

  .control-row {
    padding: 0.6rem 0.68rem;
  }

  .module-footer-nav {
    flex-direction: column;
    align-items: stretch;
  }

  .module-footer-nav .btn {
    width: 100%;
  }

  /* Glossary modal becomes a mobile bottom sheet */
  .modal-backdrop {
    padding: 0;
    align-items: flex-end;
  }

  .modal-content {
    max-height: 90vh;
    border-bottom-left-radius: 0;
    border-bottom-right-radius: 0;
  }

  .modal-body {
    grid-template-columns: 1fr;
    padding: 0.9rem;
  }
}