:root {
  --bg: #0d1117;
  --bg-2: #121923;
  --bg-3: #17202c;

  --panel: rgba(20, 27, 36, 0.9);
  --panel-strong: rgba(24, 32, 43, 0.96);
  --panel-soft: rgba(18, 24, 33, 0.72);

  --text: #ece6db;
  --text-soft: #d7d0c2;
  --muted: #aaa393;

  --border: rgba(232, 220, 194, 0.12);
  --border-strong: rgba(232, 220, 194, 0.24);

  --accent: #d8c7a2;
  --accent-strong: #f5e7c9;
  --accent-rgb: 216, 199, 162;

  --course: #6e8fc7;
  --course-rgb: 110, 143, 199;

  --practice: #b98b42;
  --practice-rgb: 185, 139, 66;

  --map: #3f9a93;
  --map-rgb: 63, 154, 147;

  --progress: #5fa56f;
  --progress-rgb: 95, 165, 111;

  --about: #8e8375;
  --about-rgb: 142, 131, 117;

  --danger: #b86a6a;
  --danger-rgb: 184, 106, 106;

  --success: #6da47b;
  --success-rgb: 109, 164, 123;

  --shadow: 0 24px 70px rgba(0, 0, 0, 0.28);
  --shadow-soft: 0 14px 36px rgba(0, 0, 0, 0.18);
  --shadow-inset: inset 0 1px 0 rgba(255, 255, 255, 0.02);

  --radius-xl: 28px;
  --radius-lg: 22px;
  --radius-md: 16px;
  --radius-sm: 12px;
  --radius-xs: 10px;
  --radius-pill: 999px;

  --content-width: 1240px;
  --narrow-width: 860px;
  --sidebar-width: 284px;
  --topbar-height: 74px;

  --transition-fast: 0.16s ease;
  --transition: 0.24s ease;
  --transition-slow: 0.34s ease;
}

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

html {
  scroll-behavior: smooth;
}

html,
body {
  min-height: 100%;
}

body {
  margin: 0;
  color: var(--text);
  overflow-x: hidden;
  background:
    radial-gradient(circle at top left, rgba(var(--accent-rgb), 0.08), transparent 24%),
    radial-gradient(circle at top right, rgba(var(--accent-rgb), 0.04), transparent 26%),
    linear-gradient(180deg, #0b0f14 0%, #10151d 36%, #111923 100%);
  font-family: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(180deg, rgba(255,255,255,0.015), transparent 22%),
    radial-gradient(circle at 20% 10%, rgba(var(--accent-rgb), 0.04), transparent 22%);
  z-index: 0;
}

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

button,
input,
select,
textarea {
  font: inherit;
}

button {
  cursor: pointer;
}

img,
svg {
  max-width: 100%;
  display: block;
}

h1,
h2,
h3,
h4 {
  margin: 0 0 0.6rem;
  font-family: "Source Serif 4", Georgia, serif;
  line-height: 1.12;
  letter-spacing: 0.01em;
  color: var(--text);
}

h1 {
  font-size: 1.8rem;
}

h2 {
  font-size: clamp(2rem, 1.68rem + 1vw, 3.15rem);
}

h3 {
  font-size: clamp(1.22rem, 1.08rem + 0.3vw, 1.62rem);
}

h4 {
  font-size: 1.08rem;
}

p,
ul,
ol,
blockquote {
  margin: 0 0 1rem;
}

strong {
  color: #f3ebdb;
  font-weight: 700;
}

ul,
ol {
  padding-left: 1.15rem;
}

::selection {
  background: rgba(var(--accent-rgb), 0.24);
}

/* Layout */

.layout,
.main,
.app-shell,
.app-screen {
  min-width: 0;
}

.app-layout {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: var(--sidebar-width) minmax(0, 1fr);
  min-height: 100vh;
}

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  padding: 0;
  border-right: 1px solid var(--border);
  background:
    linear-gradient(180deg, rgba(12, 17, 24, 0.98), rgba(16, 22, 31, 0.98));
  backdrop-filter: blur(12px);
  z-index: 30;
}

.sidebar__inner {
  display: grid;
  grid-template-rows: auto auto 1fr auto;
  gap: 20px;
  height: 100%;
  padding: 20px 18px 18px;
}

.brand {
  display: grid;
  gap: 4px;
}

.brand__eyebrow {
  margin: 0;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.16em;
  color: var(--muted);
}

.brand__title {
  margin: 0;
  font-size: 1.36rem;
  line-height: 1.04;
}

.brand__subtitle {
  margin: 0;
  color: var(--text-soft);
  font-size: 0.92rem;
}

.sidebar__toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: rgba(var(--accent-rgb), 0.05);
  color: var(--text);
  transition:
    background var(--transition),
    border-color var(--transition),
    transform var(--transition-fast);
}

.sidebar__toggle:hover {
  transform: translateY(-1px);
  border-color: var(--border-strong);
  background: rgba(var(--accent-rgb), 0.09);
}

.app-nav {
  min-width: 0;
}

.nav__list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 8px;
}

.nav__list a {
  display: flex;
  align-items: center;
  min-height: 48px;
  padding: 0 14px;
  border-radius: 14px;
  color: var(--text-soft);
  border: 1px solid transparent;
  background: transparent;
  transition:
    background var(--transition),
    border-color var(--transition),
    color var(--transition),
    transform var(--transition-fast);
}

.nav__list a:hover {
  color: var(--text);
  background: rgba(255,255,255,0.025);
  border-color: rgba(255,255,255,0.05);
  transform: translateX(1px);
}

.nav__list a.is-active {
  color: #f7f0de;
  background:
    linear-gradient(180deg, rgba(var(--accent-rgb), 0.14), rgba(var(--accent-rgb), 0.06));
  border-color: rgba(var(--accent-rgb), 0.2);
  box-shadow: var(--shadow-soft);
}

.sidebar__meta {
  display: grid;
  gap: 12px;
}

.app-shell {
  min-width: 0;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  min-height: var(--topbar-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 14px 22px;
  border-bottom: 1px solid var(--border);
  background:
    linear-gradient(180deg, rgba(13, 18, 25, 0.94), rgba(14, 20, 28, 0.9));
  backdrop-filter: blur(14px);
}

.topbar__left,
.topbar__right {
  display: flex;
  align-items: center;
  gap: 14px;
  min-width: 0;
}

.topbar__mode {
  display: inline-flex;
  align-items: center;
  min-height: 32px;
  padding: 0 12px;
  border-radius: var(--radius-pill);
  background: rgba(var(--accent-rgb), 0.08);
  border: 1px solid rgba(var(--accent-rgb), 0.16);
  color: var(--accent-strong);
  white-space: nowrap;
}

.topbar__divider {
  width: 1px;
  height: 24px;
  background: var(--border);
}

.topbar__screen {
  min-width: 0;
  font-weight: 600;
  color: var(--text-soft);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.topbar__progress {
  display: flex;
  align-items: baseline;
  gap: 8px;
  color: var(--muted);
  white-space: nowrap;
}

.topbar__progress strong {
  color: var(--accent-strong);
}

.main {
  min-width: 0;
}

.section {
  padding: 42px 28px 72px;
}

.container {
  width: min(100%, var(--content-width));
  margin: 0 auto;
}

.container--narrow {
  width: min(100%, var(--narrow-width));
}

.container--wide {
  width: min(100%, 1320px);
}

.eyebrow {
  margin-bottom: 12px;
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.16em;
  color: var(--muted);
}

.hero__title {
  font-size: clamp(2.6rem, 2rem + 1.5vw, 4.2rem);
  margin-bottom: 1rem;
}

.lead {
  max-width: 70ch;
  font-size: 1.08rem;
  color: var(--text-soft);
}

.screen-support-text {
  max-width: 78ch;
  color: var(--muted);
  margin-bottom: 0;
}

.muted {
  color: var(--muted);
}

.hidden {
  display: none !important;
}

.stack {
  display: grid;
  gap: 12px;
}

.row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.ordered-list--compact li + li {
  margin-top: 0.45rem;
}

.feature-list {
  margin: 0;
}

.feature-list li,
.ordered-list li {
  color: var(--text-soft);
}

#appView {
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.28s ease, transform 0.28s ease;
}

#appView.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* Surfaces */

.grid {
  display: grid;
  gap: 20px;
}

.grid--2 {
  grid-template-columns: 320px minmax(0, 1fr);
}

.grid--3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid--4 {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.panel {
  position: relative;
  min-width: 0;
  padding: 24px;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background:
    linear-gradient(180deg, rgba(24, 32, 43, 0.96), rgba(18, 24, 33, 0.96));
  box-shadow: var(--shadow), var(--shadow-inset);
  overflow: hidden;
}

.panel::before {
  content: "";
  position: absolute;
  inset: 0 auto auto 0;
  width: 100%;
  height: 1px;
  background: linear-gradient(90deg, rgba(var(--accent-rgb), 0.22), transparent 62%);
  pointer-events: none;
}

.panel--compact {
  padding: 18px;
}

.panel--small {
  padding: 16px;
}

.case__label {
  margin-bottom: 10px;
  font-size: 0.76rem;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--muted);
}

.badge {
  display: inline-flex;
  align-items: center;
  min-height: 30px;
  padding: 0 12px;
  border-radius: var(--radius-pill);
  border: 1px solid rgba(var(--accent-rgb), 0.18);
  background: rgba(var(--accent-rgb), 0.08);
  color: var(--accent-strong);
  font-size: 0.8rem;
  white-space: nowrap;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 18px;
  min-width: 0;
}

.actions--dashboard {
  margin-top: 28px;
}

.actions--dashboard-primary {
  margin-top: 26px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 46px;
  padding: 0 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: rgba(var(--accent-rgb), 0.04);
  color: var(--text);
  transition:
    transform var(--transition-fast),
    background var(--transition),
    border-color var(--transition),
    box-shadow var(--transition),
    opacity var(--transition),
    color var(--transition);
  white-space: nowrap;
}

.button:hover {
  transform: translateY(-1px);
  border-color: var(--border-strong);
  background: rgba(var(--accent-rgb), 0.08);
  box-shadow: var(--shadow-soft);
}

.button:active {
  transform: translateY(0);
}

.button:disabled {
  opacity: 0.42;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.button--primary {
  color: #f7f0de;
  background:
    linear-gradient(180deg, rgba(var(--accent-rgb), 0.24), rgba(var(--accent-rgb), 0.11));
  border-color: rgba(var(--accent-rgb), 0.34);
}

.button--primary:hover {
  background:
    linear-gradient(180deg, rgba(var(--accent-rgb), 0.3), rgba(var(--accent-rgb), 0.13));
}

.button--icon svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
  flex: 0 0 auto;
}

/* View transitions */

.app-screen .badge,
.app-screen .route-box,
.app-screen .case,
.app-screen .feedback,
.app-screen .subnav a,
.app-screen .subnav button,
.app-screen .topbar__mode,
.app-screen .option-button,
.app-screen .map-node-button,
.app-screen .progress-pill {
  transition:
    background var(--transition),
    border-color var(--transition),
    box-shadow var(--transition),
    color var(--transition),
    transform var(--transition-fast);
}

/* Dashboard */

.dashboard-hero {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(320px, 0.65fr);
  gap: 22px;
  align-items: stretch;
}

.dashboard-hero--focused .dashboard-hero__main {
  padding: 30px;
  border-radius: var(--radius-xl);
  border: 1px solid rgba(var(--accent-rgb), 0.16);
  background:
    linear-gradient(180deg, rgba(22, 29, 40, 0.98), rgba(17, 24, 33, 0.98)),
    radial-gradient(circle at top left, rgba(var(--accent-rgb), 0.08), transparent 34%);
  box-shadow: var(--shadow);
}

.dashboard-hero__main p:last-child {
  margin-bottom: 0;
}

.dashboard-hero__note {
  max-width: 74ch;
  color: var(--text-soft);
}

.dashboard-guide,
.dashboard-intro-card {
  align-self: stretch;
}

.dashboard-progress-inline {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 14px;
  align-items: center;
  margin-top: 20px;
  padding: 12px 14px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.02);
}

.dashboard-progress-inline__label {
  color: var(--muted);
  font-size: 0.92rem;
}

.dashboard-strip {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
  margin-top: 22px;
}

.dashboard-strip__item {
  padding-top: 20px;
  padding-bottom: 20px;
  background:
    linear-gradient(180deg, rgba(23, 31, 41, 0.94), rgba(18, 24, 33, 0.94));
}

.dashboard-strip__item--route {
  border-color: rgba(var(--accent-rgb), 0.22);
}

.dashboard-section {
  margin-top: 32px;
}

.dashboard-section--quote .grid {
  align-items: stretch;
}

.quote-panel .source-quote {
  margin-bottom: 0.8rem;
}

.dashboard-grid {
  margin-top: 24px;
  align-items: stretch;
}

.dashboard-card,
.route-panel,
.category-card {
  transition:
    transform var(--transition-fast),
    border-color var(--transition),
    box-shadow var(--transition);
}

.dashboard-card:hover,
.route-panel:hover,
.category-card:hover {
  transform: translateY(-2px);
  border-color: rgba(var(--accent-rgb), 0.22);
}

.dashboard-card--resume {
  background:
    linear-gradient(180deg, rgba(26, 35, 46, 0.98), rgba(18, 24, 33, 0.98)),
    linear-gradient(180deg, rgba(var(--accent-rgb), 0.06), transparent 55%);
}

.category-grid.category-grid--compact {
  gap: 16px;
}

.category-card h4 {
  margin-bottom: 0.42rem;
}

.source-card {
  margin-top: 26px;
}

.source-card--featured {
  margin-top: 32px;
}

.source-card--dashboard {
  border-color: rgba(var(--accent-rgb), 0.22);
}

.source-card__head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
  margin-bottom: 10px;
}

/* Section headers */

.app-section-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 18px;
  margin-bottom: 24px;
}

.app-section-head--compact {
  margin-bottom: 18px;
}

/* Course / practice shell */

.course-aside,
.practice-aside {
  align-self: start;
  position: sticky;
  top: calc(var(--topbar-height) + 20px);
}

.course-content,
.practice-content {
  min-height: 420px;
}

.content-intro-strip,
.map-summary-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 18px;
}

.aside-note {
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--border);
}

.aside-note p:last-child {
  margin-bottom: 0;
}

.subnav {
  display: grid;
  gap: 10px;
}

.subnav a,
.subnav button {
  width: 100%;
  text-align: left;
  padding: 12px 14px;
  border-radius: 12px;
  border: 1px solid transparent;
  color: var(--muted);
  background: transparent;
}

.subnav a:hover,
.subnav button:hover {
  color: var(--text);
  background: rgba(255,255,255,0.03);
  border-color: rgba(255,255,255,0.06);
  transform: translateX(2px);
}

.subnav a.is-active,
.subnav button.is-active {
  color: #f5efdd;
  border-color: rgba(var(--accent-rgb), 0.22);
  background: rgba(var(--accent-rgb), 0.08);
}

.route-box,
.case,
.feedback,
.practice-status,
.source-context-box,
.practice-intro-box {
  padding: 16px 18px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.025);
}

.route-box p:last-child,
.case p:last-child,
.feedback p:last-child,
.practice-status p:last-child {
  margin-bottom: 0;
}

.route-box--source {
  margin-top: 18px;
}

.case {
  background:
    linear-gradient(180deg, rgba(255,255,255,0.025), rgba(255,255,255,0.014));
}

.feedback {
  border-color: rgba(var(--accent-rgb), 0.2);
  background:
    linear-gradient(180deg, rgba(var(--accent-rgb), 0.1), rgba(var(--accent-rgb), 0.04));
}

.feedback + .feedback {
  margin-top: 12px;
}

.practice-status.is-complete {
  border-color: rgba(var(--success-rgb), 0.3);
  background:
    linear-gradient(180deg, rgba(var(--success-rgb), 0.14), rgba(var(--success-rgb), 0.06));
}

.course-bottom-grid,
.practice-review-grid,
.progress-summary-grid {
  margin-top: 18px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.source-quote {
  padding-left: 16px;
  border-left: 2px solid rgba(var(--accent-rgb), 0.35);
  color: var(--text-soft);
  font-style: italic;
}

/* Practice engine */

.practice-engine {
  display: grid;
  gap: 16px;
}

.interactive-block,
.interactive,
.model-panel,
.quality-panel,
.sort-panel {
  display: grid;
  gap: 16px;
  padding: 20px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  background:
    linear-gradient(180deg, rgba(22, 29, 39, 0.96), rgba(18, 24, 33, 0.96));
}

.option-list,
.freedom-options {
  display: grid;
  gap: 12px;
}

.option-button {
  width: 100%;
  justify-content: flex-start;
  align-items: flex-start;
  text-align: left;
  min-height: unset;
  padding: 14px 16px;
  white-space: normal;
  line-height: 1.5;
}

.option-button strong {
  display: inline-block;
  margin-bottom: 2px;
}

.option-button.is-active {
  border-color: rgba(var(--accent-rgb), 0.26);
  background: rgba(var(--accent-rgb), 0.1);
  color: #f5eedc;
}

.option-button.is-correct {
  border-color: rgba(var(--success-rgb), 0.34);
  background:
    linear-gradient(180deg, rgba(var(--success-rgb), 0.16), rgba(var(--success-rgb), 0.06));
}

.option-button.is-wrong {
  border-color: rgba(var(--danger-rgb), 0.32);
  background:
    linear-gradient(180deg, rgba(var(--danger-rgb), 0.15), rgba(var(--danger-rgb), 0.05));
}

.practice-toolbar {
  display: grid;
  gap: 16px;
  padding-top: 18px;
}

.practice-actions {
  margin-top: 0;
}

/* Map */

.map-legend {
  margin-bottom: 22px;
}

.map-summary-strip {
  margin-bottom: 22px;
}

.map-stages {
  display: grid;
  gap: 18px;
}

.map-stage {
  display: grid;
  gap: 14px;
}

.map-stage__head {
  border-color: rgba(var(--accent-rgb), 0.18);
}

.map-stage__nodes {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.map-node-button {
  width: 100%;
  text-align: left;
  padding: 20px;
  border-radius: var(--radius-lg);
  background:
    linear-gradient(180deg, rgba(24, 32, 43, 0.96), rgba(18, 24, 33, 0.96));
}

.map-node-button:hover {
  transform: translateY(-2px);
  border-color: rgba(var(--accent-rgb), 0.22);
}

.map-node-button__meta {
  margin-top: 10px;
  color: var(--muted);
  font-size: 0.92rem;
}

.map-node-button.is-current {
  border-color: rgba(var(--map-rgb), 0.34);
  background:
    linear-gradient(180deg, rgba(var(--map-rgb), 0.16), rgba(var(--map-rgb), 0.05));
}

.map-node-button.is-done {
  border-color: rgba(var(--progress-rgb), 0.34);
  background:
    linear-gradient(180deg, rgba(var(--progress-rgb), 0.16), rgba(var(--progress-rgb), 0.06));
}

/* Progress */

.progress-list {
  display: grid;
  gap: 18px;
  margin-top: 20px;
}

.progress-group {
  display: grid;
  gap: 14px;
}

.progress-pill {
  display: inline-flex;
  align-items: center;
  min-height: 36px;
  padding: 0 14px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.02);
  color: var(--text-soft);
}

.progress-pill.is-done {
  color: #f3eedc;
  border-color: rgba(var(--progress-rgb), 0.28);
  background:
    linear-gradient(180deg, rgba(var(--progress-rgb), 0.15), rgba(var(--progress-rgb), 0.06));
}

.progress-explainer {
  min-height: 100%;
}

/* About */

.source-card--inline {
  margin-top: 22px;
}

/* Utility refinements */

.dashboard-card p:last-child,
.route-panel p:last-child,
.category-card p:last-child,
.panel p:last-child {
  margin-bottom: 0;
}

/* Color modes by screen */

body[data-app-mode="dashboard"] {
  background:
    radial-gradient(circle at top left, rgba(var(--accent-rgb), 0.08), transparent 24%),
    radial-gradient(circle at top right, rgba(var(--accent-rgb), 0.04), transparent 26%),
    linear-gradient(180deg, #0b0f14 0%, #10151d 36%, #111923 100%);
}

body[data-app-mode="course"] {
  background:
    radial-gradient(circle at top left, rgba(var(--course-rgb), 0.08), transparent 26%),
    radial-gradient(circle at top right, rgba(var(--course-rgb), 0.05), transparent 28%),
    linear-gradient(180deg, #0b1016 0%, #101721 38%, #121b27 100%);
}

body[data-app-mode="practice"] {
  background:
    radial-gradient(circle at top left, rgba(var(--practice-rgb), 0.08), transparent 26%),
    radial-gradient(circle at top right, rgba(var(--practice-rgb), 0.04), transparent 28%),
    linear-gradient(180deg, #100f0c 0%, #16130f 36%, #1a1712 100%);
}

body[data-app-mode="map"] {
  background:
    radial-gradient(circle at top left, rgba(var(--map-rgb), 0.08), transparent 24%),
    radial-gradient(circle at top right, rgba(var(--map-rgb), 0.04), transparent 28%),
    linear-gradient(180deg, #0b1111 0%, #0f1718 38%, #121d1d 100%);
}

body[data-app-mode="progress"] {
  background:
    radial-gradient(circle at top left, rgba(var(--progress-rgb), 0.08), transparent 24%),
    radial-gradient(circle at top right, rgba(var(--progress-rgb), 0.04), transparent 28%),
    linear-gradient(180deg, #0c110d 0%, #101713 38%, #121c16 100%);
}

body[data-app-mode="about"] {
  background:
    radial-gradient(circle at top left, rgba(var(--about-rgb), 0.08), transparent 24%),
    radial-gradient(circle at top right, rgba(var(--about-rgb), 0.04), transparent 28%),
    linear-gradient(180deg, #0f0f10 0%, #171719 38%, #1b1a1a 100%);
}

body[data-app-mode="course"] .badge,
body[data-app-mode="course"] .topbar__mode,
body[data-app-mode="course"] .subnav a.is-active,
body[data-app-mode="course"] .subnav button.is-active {
  background: rgba(var(--course-rgb), 0.12);
  border-color: rgba(var(--course-rgb), 0.24);
  color: #d9e5ff;
}

body[data-app-mode="practice"] .badge,
body[data-app-mode="practice"] .topbar__mode,
body[data-app-mode="practice"] .subnav a.is-active,
body[data-app-mode="practice"] .subnav button.is-active {
  background: rgba(var(--practice-rgb), 0.13);
  border-color: rgba(var(--practice-rgb), 0.24);
  color: #ffe7bf;
}

body[data-app-mode="map"] .badge,
body[data-app-mode="map"] .topbar__mode {
  background: rgba(var(--map-rgb), 0.12);
  border-color: rgba(var(--map-rgb), 0.24);
  color: #d2fffa;
}

body[data-app-mode="progress"] .badge,
body[data-app-mode="progress"] .topbar__mode {
  background: rgba(var(--progress-rgb), 0.12);
  border-color: rgba(var(--progress-rgb), 0.24);
  color: #def8e2;
}

body[data-app-mode="about"] .badge,
body[data-app-mode="about"] .topbar__mode {
  background: rgba(var(--about-rgb), 0.12);
  border-color: rgba(var(--about-rgb), 0.24);
  color: #ede1d4;
}

body[data-app-mode="course"] .route-box,
body[data-app-mode="course"] .feedback,
body[data-app-mode="course"] .source-context-box {
  border-color: rgba(var(--course-rgb), 0.16);
}

body[data-app-mode="practice"] .route-box,
body[data-app-mode="practice"] .feedback,
body[data-app-mode="practice"] .practice-status,
body[data-app-mode="practice"] .practice-intro-box {
  border-color: rgba(var(--practice-rgb), 0.18);
}

body[data-app-mode="map"] .map-stage__head,
body[data-app-mode="map"] .map-node-button:hover {
  border-color: rgba(var(--map-rgb), 0.24);
}

body[data-app-mode="progress"] .progress-pill.is-done {
  border-color: rgba(var(--progress-rgb), 0.32);
}

/* Responsive */

@media (max-width: 1220px) {
  .grid--3,
  .grid--4,
  .dashboard-strip,
  .map-stage__nodes {
    grid-template-columns: 1fr 1fr;
  }

  .dashboard-grid,
  .category-grid {
    grid-template-columns: 1fr 1fr;
  }

  .dashboard-hero {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 980px) {
  .app-layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: sticky;
    top: 0;
    height: auto;
    border-right: none;
    border-bottom: 1px solid var(--border);
  }

  .sidebar__inner {
    grid-template-rows: auto auto auto;
    height: auto;
    padding: 14px 16px 16px;
    gap: 14px;
  }

  .sidebar__toggle {
    display: inline-flex;
  }

  .app-nav {
    display: none;
  }

  .sidebar.open .app-nav {
    display: block;
  }

  .sidebar__meta {
    display: none;
  }

  .grid--2,
  .grid--3,
  .grid--4,
  .dashboard-grid,
  .category-grid,
  .dashboard-strip,
  .map-stage__nodes,
  .course-bottom-grid,
  .practice-review-grid,
  .progress-summary-grid {
    grid-template-columns: 1fr;
  }

  .course-aside,
  .practice-aside {
    position: static;
  }

  .section {
    padding: 30px 18px 56px;
  }
}

@media (max-width: 860px) {
  .topbar {
    padding: 14px 16px;
    flex-direction: column;
    align-items: stretch;
  }

  .topbar__left,
  .topbar__right {
    width: 100%;
    justify-content: space-between;
  }

  .topbar__right {
    flex-direction: column;
    align-items: stretch;
  }

  .topbar__right .button,
  .practice-actions .button,
  .actions .button {
    width: 100%;
    justify-content: center;
    white-space: normal;
  }

  .app-section-head {
    flex-direction: column;
    align-items: stretch;
  }

  .source-card__head {
    flex-direction: column;
    align-items: flex-start;
  }

  .panel,
  .case,
  .interactive-block,
  .interactive,
  .model-panel,
  .quality-panel,
  .sort-panel {
    padding: 18px;
  }

  .hero__title {
    font-size: clamp(2.1rem, 1.8rem + 1vw, 3rem);
  }
}

@media (max-width: 560px) {
  .topbar__left {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
  }

  .topbar__divider {
    display: none;
  }

  .topbar__screen {
    white-space: normal;
  }

  .dashboard-hero--focused .dashboard-hero__main {
    padding: 22px 18px;
  }

  .button {
    min-height: 44px;
    padding: 0 16px;
  }

  .progress-pill {
    width: 100%;
    justify-content: center;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation: none !important;
    transition: none !important;
    scroll-behavior: auto !important;
  }

  #appView {
    opacity: 1;
    transform: none;
  }
}