:root {
  color-scheme: dark;
  --bg: #130f0d;
  --panel: rgba(34, 25, 20, 0.78);
  --panel-strong: rgba(45, 33, 26, 0.94);
  --line: rgba(222, 165, 132, 0.22);
  --line-strong: rgba(244, 102, 35, 0.58);
  --text: #fff4ea;
  --muted: rgba(255, 244, 234, 0.7);
  --faint: rgba(255, 244, 234, 0.48);
  --mint: #f46623;
  --amber: #dea584;
  --rust-brown: #7a3f1c;
  --rust-black: #15110f;
  --red: #ff7d86;
  --green: #9bd77f;
  --shadow: 0 24px 80px rgba(0, 0, 0, 0.46);
  --focus: 0 0 0 4px rgba(244, 102, 35, 0.28);
  font-family:
    ui-monospace, "SFMono-Regular", "SF Mono", Menlo, Consolas, "Liberation Mono",
    monospace;
}

[data-theme="light"] {
  color-scheme: light;
  --bg: #f8efe4;
  --panel: rgba(255, 250, 243, 0.82);
  --panel-strong: rgba(255, 250, 243, 0.96);
  --line: rgba(122, 63, 28, 0.18);
  --line-strong: rgba(184, 78, 23, 0.5);
  --text: #241812;
  --muted: rgba(36, 24, 18, 0.72);
  --faint: rgba(36, 24, 18, 0.48);
  --mint: #c64f1a;
  --amber: #8b4b25;
  --rust-brown: #7a3f1c;
  --rust-black: #211713;
  --red: #b73545;
  --green: #27723a;
  --shadow: 0 24px 70px rgba(92, 54, 26, 0.18);
  --focus: 0 0 0 4px rgba(198, 79, 26, 0.24);
}

* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
  background: var(--bg);
}

body {
  min-height: 100vh;
  margin: 0;
  color: var(--text);
  background: var(--bg);
}

.theme-root {
  min-height: 100vh;
  background:
    radial-gradient(circle at 18% 18%, rgba(244, 102, 35, 0.22), transparent 28%),
    radial-gradient(circle at 78% 8%, rgba(222, 165, 132, 0.2), transparent 22%),
    radial-gradient(circle at 72% 78%, rgba(122, 63, 28, 0.18), transparent 30%),
    linear-gradient(135deg, var(--bg) 0%, var(--bg) 46%, var(--bg) 100%);
  color: var(--text);
}

.theme-root::before {
  position: fixed;
  inset: 0;
  z-index: -2;
  pointer-events: none;
  content: "";
  background-image:
    linear-gradient(rgba(222, 165, 132, 0.07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(222, 165, 132, 0.07) 1px, transparent 1px);
  background-size: 40px 40px;
  mask-image: linear-gradient(to bottom, black, transparent 72%);
}

.theme-root::after {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  content: "";
  background: linear-gradient(120deg, transparent, rgba(244, 102, 35, 0.09), transparent);
  opacity: 0.54;
}

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

button,
input,
textarea {
  font: inherit;
}

button {
  color: inherit;
}

.app-shell {
  width: min(1440px, calc(100vw - 32px));
  min-height: 100vh;
  margin: 0 auto;
  padding: 24px 0 48px;
}

.topbar {
  position: sticky;
  top: 12px;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 14px 16px;
  margin-bottom: 28px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: color-mix(in srgb, var(--panel-strong) 78%, transparent);
  backdrop-filter: blur(18px);
  box-shadow: 0 12px 50px rgba(0, 0, 0, 0.28);
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 220px;
}

.brand-mark {
  position: relative;
  display: grid;
  width: 40px;
  height: 40px;
  place-items: center;
  border: 1px solid color-mix(in srgb, var(--mint) 58%, var(--amber));
  border-radius: 50%;
  color: var(--rust-black);
  background:
    radial-gradient(circle at center, var(--amber) 0 38%, transparent 39%),
    conic-gradient(from 10deg, var(--mint), var(--amber), var(--rust-brown), var(--mint));
  box-shadow: 0 0 28px rgba(244, 102, 35, 0.24);
  font-weight: 950;
  overflow: hidden;
}

.brand-mark img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.brand-mark::before {
  position: absolute;
  inset: -6px;
  z-index: -1;
  border-radius: 50%;
  content: "";
  background: repeating-conic-gradient(
    from 0deg,
    rgba(244, 102, 35, 0.48) 0deg 8deg,
    transparent 8deg 18deg
  );
  opacity: 0.6;
}

.brand-title {
  margin: 0;
  font-size: 15px;
  font-weight: 800;
  letter-spacing: -0.04em;
}

.brand-subtitle {
  margin: 2px 0 0;
  color: var(--faint);
  font-size: 11px;
}

.nav {
  display: flex;
  gap: 8px;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
}

.toolbar {
  display: flex;
  gap: 8px;
  align-items: center;
}

.nav-link,
.ghost-button,
.primary-button,
.option-button,
.tiny-button {
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.03);
  cursor: pointer;
  transition:
    border-color 160ms ease,
    background 160ms ease,
    transform 160ms ease,
    box-shadow 160ms ease;
}

.nav-link {
  padding: 10px 14px;
  color: var(--muted);
  font-size: 12px;
}

.nav-link:hover,
.nav-link.active,
.ghost-button:hover,
.option-button:hover,
.tiny-button:hover {
  border-color: var(--line-strong);
  color: var(--text);
  background: color-mix(in srgb, var(--mint) 13%, transparent);
}

.nav-link.active {
  color: var(--rust-black);
  background: linear-gradient(135deg, var(--mint), var(--amber));
  box-shadow: 0 0 30px rgba(244, 102, 35, 0.24);
}

.shell-grid {
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  gap: 24px;
  align-items: start;
}

.side-rail,
.panel,
.hero-card,
.exercise-panel,
.stat-card {
  border: 1px solid var(--line);
  background: var(--panel);
  box-shadow: var(--shadow);
  backdrop-filter: blur(20px);
}

.side-rail {
  position: sticky;
  top: 104px;
  height: calc(100vh - 128px);
  padding: 16px;
  overflow: auto;
  border-radius: 30px;
}

.rail-title,
.section-title {
  margin: 0;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: -0.03em;
}

.rail-caption,
.muted,
.card-text,
.lesson-summary,
.stat-label {
  color: var(--muted);
}

.rail-caption {
  margin: 6px 0 16px;
  font-size: 12px;
  line-height: 1.6;
}

.progress-track {
  height: 10px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.04);
}

.progress-fill {
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--mint), var(--amber), var(--rust-brown));
  box-shadow: 0 0 20px rgba(244, 102, 35, 0.28);
}

.rail-list {
  display: grid;
  gap: 10px;
  margin-top: 18px;
}

.rail-item {
  display: grid;
  grid-template-columns: 14px 1fr auto;
  gap: 10px;
  align-items: start;
  padding: 12px;
  border: 1px solid color-mix(in srgb, var(--amber) 16%, transparent);
  border-radius: 18px;
  background: color-mix(in srgb, var(--panel-strong) 38%, transparent);
}

.status-dot {
  width: 10px;
  height: 10px;
  margin-top: 4px;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  background: color-mix(in srgb, var(--amber) 16%, transparent);
}

.status-dot.done {
  background: var(--mint);
  box-shadow: 0 0 20px rgba(244, 102, 35, 0.38);
}

.rail-item-title {
  display: block;
  margin: 0;
  font-size: 12px;
  font-weight: 800;
}

.rail-item-meta {
  display: block;
  margin: 4px 0 0;
  color: var(--faint);
  font-size: 11px;
}

.main-stack {
  display: grid;
  gap: 24px;
  min-width: 0;
}

.hero-card {
  position: relative;
  min-height: 420px;
  padding: clamp(28px, 5vw, 64px);
  overflow: hidden;
  border-radius: 42px;
  background:
    linear-gradient(135deg, rgba(244, 102, 35, 0.2), transparent 46%),
    linear-gradient(160deg, rgba(222, 165, 132, 0.2), transparent 44%),
    radial-gradient(circle at 85% 80%, rgba(122, 63, 28, 0.24), transparent 34%),
    var(--panel);
}

.hero-card::after {
  position: absolute;
  right: -80px;
  bottom: -120px;
  width: 360px;
  height: 360px;
  border: 1px solid rgba(244, 102, 35, 0.34);
  border-radius: 50%;
  content: "";
  background: repeating-conic-gradient(
    from 12deg,
    transparent 0deg 10deg,
    rgba(244, 102, 35, 0.08) 10deg 18deg
  );
  box-shadow: inset 0 0 50px rgba(244, 102, 35, 0.14);
}

.eyebrow {
  display: inline-flex;
  gap: 8px;
  align-items: center;
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--mint);
  background: color-mix(in srgb, var(--mint) 10%, transparent);
  font-size: 12px;
}

.hero-title {
  max-width: 900px;
  margin: 24px 0 18px;
  font-size: clamp(44px, 8vw, 104px);
  line-height: 0.92;
  letter-spacing: -0.1em;
}

.hero-title span {
  display: block;
  color: var(--mint);
}

.hero-copy {
  max-width: 720px;
  margin: 0 0 28px;
  color: var(--muted);
  font-size: clamp(15px, 1.6vw, 18px);
  line-height: 1.8;
}

.hero-actions,
.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
}

.primary-button,
.ghost-button,
.tiny-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 18px;
  font-size: 13px;
  font-weight: 800;
}

.primary-button {
  border-color: transparent;
  color: var(--rust-black);
  background: linear-gradient(135deg, var(--mint), var(--amber));
  box-shadow: 0 0 36px rgba(244, 102, 35, 0.26);
}

.primary-button:hover {
  transform: translateY(-1px);
  box-shadow: 0 0 46px rgba(244, 102, 35, 0.38);
}

.ghost-button,
.tiny-button {
  color: var(--text);
}

.tiny-button {
  min-height: 34px;
  padding: 0 12px;
  font-size: 11px;
}

.metric-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin-top: 36px;
}

.metric-card,
.panel,
.stat-card {
  border-radius: 28px;
  padding: 18px;
}

.metric-card {
  border: 1px solid color-mix(in srgb, var(--amber) 18%, transparent);
  background:
    linear-gradient(180deg, color-mix(in srgb, var(--amber) 8%, transparent), transparent),
    rgba(0, 0, 0, 0.14);
}

.metric-value,
.stat-value {
  margin: 0;
  font-variant-numeric: tabular-nums;
  font-size: 30px;
  font-weight: 900;
  letter-spacing: -0.06em;
}

.metric-label {
  margin: 4px 0 0;
  color: var(--faint);
  font-size: 12px;
}

.panel-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

.panel.full {
  grid-column: 1 / -1;
}

.section-title {
  font-size: 20px;
}

.section-copy {
  margin: 8px 0 0;
  color: var(--muted);
  line-height: 1.7;
}

.lesson-grid,
.card-grid,
.stats-grid {
  display: grid;
  gap: 16px;
}

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

.lesson-card,
.knowledge-card,
.stage-card {
  position: relative;
  padding: 18px;
  border: 1px solid color-mix(in srgb, var(--amber) 18%, transparent);
  border-radius: 26px;
  background: color-mix(in srgb, var(--panel-strong) 34%, transparent);
}

.lesson-card:hover,
.knowledge-card:hover,
.stage-card:hover {
  border-color: var(--line-strong);
  background: color-mix(in srgb, var(--mint) 8%, var(--panel));
}

.lesson-title,
.card-title {
  margin: 0;
  font-size: 16px;
  font-weight: 900;
  letter-spacing: -0.04em;
}

.lesson-summary,
.card-text {
  margin: 10px 0 14px;
  font-size: 13px;
  line-height: 1.65;
}

.tag-row,
.goal-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 12px 0;
  padding: 0;
  list-style: none;
}

.tag,
.pill {
  display: inline-flex;
  align-items: center;
  min-height: 26px;
  padding: 4px 9px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  font-size: 11px;
}

.pill.strong {
  color: var(--mint);
  border-color: var(--line-strong);
  background: color-mix(in srgb, var(--mint) 12%, transparent);
}

.code-block {
  position: relative;
  overflow: auto;
  padding: 42px 16px 16px 48px;
  border: 1px solid color-mix(in srgb, var(--amber) 22%, transparent);
  border-radius: 22px;
  color: color-mix(in srgb, var(--amber) 75%, var(--text));
  background:
    linear-gradient(90deg, color-mix(in srgb, var(--mint) 7%, transparent), transparent),
    rgba(12, 8, 6, 0.78);
  line-height: 1.7;
  white-space: pre-wrap;
}

.code-block::before {
  position: absolute;
  top: 0;
  right: 0;
  left: 0;
  height: 30px;
  padding-left: 54px;
  border-bottom: 1px solid color-mix(in srgb, var(--amber) 16%, transparent);
  color: var(--faint);
  background: rgba(255, 255, 255, 0.035);
  content: "main.rs";
  font-size: 11px;
  line-height: 30px;
}

.code-block::after {
  position: absolute;
  top: 10px;
  left: 14px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--red);
  box-shadow:
    14px 0 0 var(--amber),
    28px 0 0 var(--green);
  content: "";
}

.exercise-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
}

.level-pill {
  color: var(--amber);
}

.exercise-panel {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 340px;
  gap: 18px;
  padding: 20px;
  border-radius: 34px;
}

.exercise-title {
  margin: 10px 0;
  font-size: clamp(28px, 4vw, 56px);
  line-height: 0.95;
  letter-spacing: -0.08em;
}

.exercise-prompt {
  color: var(--muted);
  line-height: 1.75;
}

.answer-stack {
  display: grid;
  gap: 10px;
  margin-top: 16px;
}

.option-button {
  width: 100%;
  min-height: 48px;
  padding: 12px 14px;
  color: var(--text);
  text-align: left;
}

.option-button.selected {
  border-color: var(--mint);
  background: color-mix(in srgb, var(--mint) 16%, transparent);
}

.text-input {
  width: 100%;
  min-height: 48px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 18px;
  color: var(--text);
  background: rgba(0, 0, 0, 0.22);
  outline: none;
}

.text-input:focus {
  border-color: var(--line-strong);
  box-shadow: var(--focus);
}

.feedback {
  margin-top: 18px;
  padding: 16px;
  border: 1px solid color-mix(in srgb, var(--amber) 22%, transparent);
  border-radius: 22px;
  background: rgba(255, 255, 255, 0.035);
}

.feedback.correct {
  border-color: rgba(140, 248, 169, 0.42);
}

.feedback.wrong {
  border-color: rgba(255, 125, 134, 0.42);
}

.feedback-title {
  margin: 0 0 8px;
  color: var(--mint);
  font-weight: 900;
}

.feedback.wrong .feedback-title {
  color: var(--red);
}

.demo-panel {
  display: flex;
  flex-direction: column;
  gap: 14px;
  padding: 16px;
  border: 1px solid color-mix(in srgb, var(--amber) 34%, transparent);
  border-radius: 26px;
  background:
    linear-gradient(180deg, color-mix(in srgb, var(--amber) 10%, transparent), transparent),
    color-mix(in srgb, var(--panel-strong) 28%, transparent);
}

.demo-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
}

.demo-title {
  margin: 0;
  color: var(--amber);
  font-size: 14px;
  font-weight: 900;
}

.guide-list {
  display: grid;
  gap: 8px;
  padding: 10px;
  border: 1px solid color-mix(in srgb, var(--amber) 18%, transparent);
  border-radius: 18px;
  background: color-mix(in srgb, var(--rust-black) 18%, transparent);
}

.guide-step {
  display: grid;
  grid-template-columns: 28px 1fr;
  gap: 8px;
  margin: 0;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.55;
}

.guide-step span {
  color: var(--mint);
  font-variant-numeric: tabular-nums;
  font-weight: 900;
}

.demo-output {
  color: var(--amber);
}

.empty-state {
  padding: 40px;
  border: 1px dashed var(--line);
  border-radius: 28px;
  color: var(--muted);
  text-align: center;
}

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

.stat-card {
  min-height: 132px;
}

.stat-label {
  margin: 0 0 12px;
  font-size: 12px;
}

.weak-list {
  display: grid;
  gap: 10px;
  margin-top: 16px;
}

.nav-link:focus-visible,
.primary-button:focus-visible,
.ghost-button:focus-visible,
.tiny-button:focus-visible,
.option-button:focus-visible,
.rail-item:focus-visible,
.brand:focus-visible,
.pill:focus-visible,
.text-input:focus-visible {
  outline: none;
  box-shadow: var(--focus);
}

.option-button:active,
.primary-button:active,
.ghost-button:active,
.tiny-button:active {
  transform: translateY(1px) scale(0.99);
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 1ms !important;
    animation-duration: 1ms !important;
    animation-iteration-count: 1 !important;
  }
}

@media (max-width: 1060px) {
  .shell-grid,
  .exercise-panel {
    grid-template-columns: 1fr;
  }

  .main-stack {
    order: 1;
  }

  .side-rail {
    order: 2;
    position: static;
    height: auto;
  }

  .panel-grid,
  .lesson-grid,
  .stats-grid,
  .metric-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 720px) {
  .app-shell {
    width: min(100vw - 20px, 720px);
    padding-top: 10px;
  }

  .topbar {
    position: static;
    align-items: flex-start;
    border-radius: 24px;
    flex-direction: column;
  }

  .brand {
    min-width: 0;
  }

  .nav {
    justify-content: flex-start;
  }

  .hero-card {
    min-height: auto;
    border-radius: 30px;
  }

  .hero-title {
    font-size: clamp(40px, 12vw, 46px);
    line-height: 1;
    letter-spacing: -0.065em;
  }

  .hero-card::after {
    right: -120px;
    bottom: -84px;
    width: 290px;
    height: 290px;
    opacity: 0.48;
  }

  .exercise-panel,
  .hero-card,
  .panel,
  .side-rail {
    border-radius: 24px;
  }

  .exercise-title {
    font-size: 40px;
    letter-spacing: -0.06em;
  }
}