:root {
  color-scheme: light;
  --ink: #18202f;
  --muted: #667085;
  --line: #d9e0ea;
  --paper: #f6f7fb;
  --panel: #ffffff;
  --accent: #1f7a68;
  --accent-dark: #145c4e;
  --warm: #c75532;
  --blue: #2b65b1;
  --code: #111827;
  --success: #117c45;
  --danger: #b42318;
  --shadow: 0 18px 50px rgba(29, 41, 57, 0.12);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;
  background:
    linear-gradient(135deg, rgba(31, 122, 104, 0.08), transparent 32%),
    linear-gradient(315deg, rgba(199, 85, 50, 0.08), transparent 38%),
    var(--paper);
}

button,
textarea,
select {
  font: inherit;
}

button {
  min-height: 42px;
  border: 0;
  border-radius: 8px;
  cursor: pointer;
}

button:disabled {
  cursor: not-allowed;
}

button:focus-visible,
textarea:focus-visible,
select:focus-visible {
  outline: 3px solid rgba(43, 101, 177, 0.28);
  outline-offset: 2px;
}

.app-shell {
  width: min(1180px, calc(100% - 32px));
  margin: 32px auto;
}

.workspace {
  display: grid;
  grid-template-columns: 320px minmax(0, 1fr);
  min-height: calc(100vh - 64px);
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  box-shadow: var(--shadow);
}

.sidebar {
  display: flex;
  flex-direction: column;
  gap: 24px;
  padding: 24px;
  border-right: 1px solid var(--line);
  background: #f9fafc;
}

.brand {
  display: grid;
  grid-template-columns: 52px 1fr;
  gap: 14px;
  align-items: center;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 52px;
  height: 52px;
  border-radius: 8px;
  color: #fff;
  font-weight: 800;
  background: conic-gradient(from 220deg, var(--accent), var(--blue), var(--warm), var(--accent));
}

.eyebrow,
.tiny-label,
.progress-label {
  margin: 0;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 0;
  font-size: 1.12rem;
  line-height: 1.35;
}

.progress-panel {
  display: grid;
  gap: 10px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.progress-summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.meter {
  height: 10px;
  overflow: hidden;
  border-radius: 99px;
  background: #e7ecf3;
}

.meter span {
  display: block;
  width: 0%;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--accent), var(--blue));
  transition: width 180ms ease;
}

.motivation-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 6px;
  padding-top: 10px;
  border-top: 1px solid var(--line);
}

.motivation-stats > div {
  display: grid;
  gap: 2px;
  min-width: 0;
  padding: 7px 4px;
  border-radius: 6px;
  background: #f5f7fa;
  text-align: center;
}

.motivation-stats span,
.daily-goal span {
  color: var(--muted);
  font-size: 0.7rem;
  font-weight: 800;
}

.motivation-stats strong {
  font-size: 0.92rem;
}

.daily-goal {
  display: grid;
  gap: 7px;
  padding-top: 2px;
}

.daily-goal > div:first-child {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.daily-meter {
  height: 7px;
  overflow: hidden;
  border-radius: 99px;
  background: #e7ecf3;
}

.daily-meter span {
  display: block;
  width: 0%;
  height: 100%;
  border-radius: inherit;
  background: #dd7d32;
  transition: width 180ms ease;
}

.motivation-message {
  margin: 0;
  color: var(--ink);
  font-size: 0.78rem;
  font-weight: 700;
  line-height: 1.55;
}

.achievement-row {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  min-height: 24px;
}

.achievement-badge {
  display: inline-flex;
  align-items: center;
  min-height: 24px;
  padding: 2px 7px;
  border: 1px solid #d7b46a;
  border-radius: 6px;
  color: #76500e;
  font-size: 0.68rem;
  font-weight: 900;
  background: #fff7df;
}

.achievement-empty {
  color: var(--muted);
  font-size: 0.7rem;
}

.category-filters {
  display: grid;
  gap: 12px;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.category-filter {
  display: grid;
  gap: 7px;
}

.category-filter span {
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 800;
}

.category-filter select {
  width: 100%;
  min-height: 42px;
  padding: 0 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--ink);
  font: inherit;
  font-weight: 700;
  background: #fff;
}

.category-filter select:disabled {
  color: var(--muted);
  background: #f2f4f7;
  cursor: not-allowed;
}

.category-description {
  margin: 0;
  color: var(--muted);
  font-size: 0.78rem;
  line-height: 1.55;
}

.assessment-launcher {
  display: grid;
  gap: 10px;
  padding-top: 16px;
  border-top: 1px solid var(--line);
}

.assessment-launcher h2 {
  margin: 3px 0 0;
  font-size: 1rem;
}

.assessment-options {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 6px;
}

.assessment-options button {
  display: grid;
  place-items: center;
  min-width: 0;
  padding: 8px 4px;
  border: 1px solid var(--line);
  color: var(--ink);
  font-weight: 800;
  background: #fff;
}

.assessment-options button:hover {
  border-color: var(--blue);
  color: var(--blue);
}

.assessment-options button span {
  color: var(--muted);
  font-size: 0.7rem;
  font-weight: 700;
}

.assessment-panel {
  display: grid;
  gap: 14px;
  margin-bottom: 22px;
  padding: 16px 18px;
  border: 1px solid #a9c7bd;
  border-left: 5px solid var(--accent);
  border-radius: 8px;
  background: #f2faf7;
}

.assessment-panel[hidden] {
  display: none;
}

.assessment-status,
.assessment-controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.assessment-status > div {
  display: grid;
  gap: 3px;
}

.assessment-status strong {
  font-size: 1.05rem;
}

#assessmentScore {
  font-weight: 800;
}

.lesson-tab.is-incorrect .status-dot {
  color: #fff;
  background: var(--danger);
}

.assessment-result {
  padding-top: 12px;
  border-top: 1px solid #c5ddd5;
  line-height: 1.65;
}

.assessment-result strong {
  display: block;
  font-size: 1.35rem;
}

.assessment-result span {
  display: block;
  margin-top: 8px;
  color: var(--danger);
  font-weight: 700;
}

.workspace.is-assessment .concept-grid,
.workspace.is-assessment .pattern-reveal,
.workspace.is-assessment .mini-console,
.workspace.is-assessment #hintButton,
.workspace.is-assessment #answerButton {
  display: none;
}

.workspace.is-assessment .lesson-list .lesson-tab:not(.is-test-question) {
  display: none;
}

.workspace.is-assessment .category-filters,
.workspace.is-assessment .assessment-launcher {
  opacity: 0.55;
  pointer-events: none;
}

.lesson-list {
  display: grid;
  gap: 8px;
}

.lesson-tab {
  display: grid;
  grid-template-columns: 30px 1fr auto;
  gap: 10px;
  align-items: center;
  width: 100%;
  padding: 11px 12px;
  border: 1px solid transparent;
  color: var(--ink);
  text-align: left;
  background: transparent;
}

.lesson-tab:hover {
  background: #eef3f7;
}

.lesson-tab.is-active {
  border-color: #bad7d0;
  background: #eaf6f2;
}

.lesson-tab.is-complete .status-dot {
  color: #fff;
  background: var(--success);
}

.status-dot {
  display: grid;
  place-items: center;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 800;
  background: #e7ecf3;
}

.lesson-tab strong,
.lesson-tab span {
  display: block;
}

.lesson-tab strong {
  font-size: 0.94rem;
}

.lesson-tab span {
  color: var(--muted);
  font-size: 0.78rem;
}

.lesson-area {
  display: grid;
  align-content: start;
  gap: 20px;
  padding: 28px;
}

.lesson-header {
  display: flex;
  gap: 16px;
  align-items: start;
  justify-content: space-between;
}

.lesson-header h2 {
  margin-bottom: 0;
  font-size: clamp(1.8rem, 3vw, 3rem);
  line-height: 1.1;
}

.level-pill {
  flex: 0 0 auto;
  padding: 7px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--accent-dark);
  font-size: 0.86rem;
  font-weight: 700;
  background: #f5fbf9;
}

.concept-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 16px;
}

.concept-card,
.exercise-panel,
.mini-console {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.concept-card {
  padding: 18px;
}

.concept-card-wide {
  grid-column: 1 / -1;
}

.concept-card h3,
.exercise-panel h3,
.mini-console h3,
.pattern-reveal h3 {
  margin-bottom: 8px;
  font-size: 1rem;
}

.concept-card p,
.mini-console p {
  margin-bottom: 0;
  color: #384252;
  line-height: 1.7;
}

pre {
  margin: 0;
  white-space: pre-wrap;
}

code,
textarea {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}

.concept-card pre {
  padding: 14px;
  border-radius: 8px;
  color: #e6edf7;
  background: var(--code);
}

.learning-actions {
  display: flex;
  justify-content: flex-end;
  margin-top: 12px;
}

.pattern-reveal {
  padding: 18px;
  border: 1px solid #9dc9bf;
  border-left: 5px solid var(--accent);
  border-radius: 8px;
  background: #f3faf7;
}

.pattern-reveal[hidden] {
  display: none;
}

.pattern-reveal pre {
  padding: 14px;
  border-radius: 8px;
  color: #e6edf7;
  background: var(--code);
}

.exercise-panel {
  overflow: hidden;
}

.exercise-topline {
  display: flex;
  gap: 16px;
  align-items: center;
  justify-content: space-between;
  padding: 18px 18px 12px;
}

.exercise-topline h3 {
  margin-bottom: 0;
}

.code-frame {
  display: grid;
  padding: 18px;
  color: #d7e4f4;
  background: var(--code);
}

.code-frame code {
  line-height: 1.65;
}

textarea {
  width: 100%;
  min-height: 76px;
  margin: 8px 0;
  padding: 12px;
  resize: vertical;
  border: 1px solid #44546c;
  border-radius: 8px;
  color: #f7fbff;
  caret-color: #ffffff;
  background: #1b2434;
}

textarea::placeholder {
  color: #98a7bd;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  padding: 16px 18px;
  border-top: 1px solid var(--line);
}

.primary-button {
  padding: 0 18px;
  color: #fff;
  font-weight: 800;
  background: var(--accent);
}

.primary-button:hover {
  background: var(--accent-dark);
}

.secondary-button,
.ghost-button {
  padding: 0 14px;
  color: var(--ink);
  font-weight: 700;
  background: #edf2f7;
}

.secondary-button:hover,
.ghost-button:hover {
  background: #dfe7f0;
}

.primary-button:disabled {
  cursor: wait;
  opacity: 0.65;
}

.execution-panel {
  margin: 0 18px 16px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #f8fafc;
}

.execution-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 10px 14px;
  border-bottom: 1px solid var(--line);
}

.execution-header span,
.execution-header strong {
  font-size: 0.78rem;
  font-weight: 800;
}

.execution-header strong {
  color: var(--muted);
}

.execution-panel pre {
  max-height: 260px;
  overflow: auto;
  padding: 14px;
  color: #334155;
  background: #f8fafc;
}

.execution-panel code {
  line-height: 1.65;
}

.execution-panel[data-state="running"] .execution-header strong {
  color: var(--blue);
}

.execution-panel[data-state="success"] {
  border-color: #95d5b2;
}

.execution-panel[data-state="success"] .execution-header strong {
  color: var(--success);
}

.execution-panel[data-state="error"] {
  border-color: #f4b8ae;
}

.execution-panel[data-state="error"] .execution-header strong {
  color: var(--danger);
}

.solution-reveal {
  margin: 0 18px 16px;
  padding: 14px;
  border: 1px solid #f4b8ae;
  border-left: 4px solid var(--danger);
  border-radius: 8px;
  color: var(--danger);
  background: #fff7f5;
}

.solution-reveal[hidden] {
  display: none;
}

.solution-reveal span {
  display: block;
  margin-bottom: 8px;
  font-size: 0.78rem;
  font-weight: 800;
}

.solution-reveal code {
  color: #8f1f17;
  line-height: 1.65;
}

.feedback {
  min-height: 58px;
  padding: 14px 18px 18px;
  color: #384252;
  border-top: 1px solid var(--line);
  line-height: 1.55;
}

.feedback.is-success {
  color: var(--success);
  background: #edf8f2;
}

.feedback.is-error {
  color: var(--danger);
  background: #fff2ef;
}

.feedback.is-info {
  color: #24518d;
  background: #eef5ff;
}

.mini-console {
  padding: 18px;
  border-left: 5px solid var(--warm);
}

@media (max-width: 850px) {
  .app-shell {
    width: min(100% - 20px, 680px);
    margin: 10px auto;
  }

  .workspace {
    grid-template-columns: 1fr;
    min-height: auto;
  }

  .sidebar {
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

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

  .lesson-tab {
    grid-template-columns: 26px 1fr;
  }

  .lesson-tab .topic-number {
    display: none;
  }

  .concept-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 560px) {
  .lesson-area,
  .sidebar {
    padding: 18px;
  }

  .brand {
    grid-template-columns: 44px 1fr;
  }

  .brand-mark {
    width: 44px;
    height: 44px;
  }

  .lesson-list {
    grid-template-columns: 1fr;
  }

  .lesson-header,
  .exercise-topline {
    align-items: stretch;
    flex-direction: column;
  }

  .level-pill {
    width: fit-content;
  }

  .actions {
    display: grid;
  }

  .assessment-status,
  .assessment-controls {
    align-items: stretch;
    flex-direction: column;
  }

  button {
    width: 100%;
  }
}