:root {
  color-scheme: light;
  --page-bg: #151515;
  --app-bg: #f7efe3;
  --panel: #fffdfa;
  --panel-soft: #f5ecde;
  --rail: #efe3d1;
  --line: #e2d3b9;
  --line-strong: #c9ae82;
  --text: #202423;
  --muted: #756f65;
  --faint: #aaa295;
  --brand: #6f8f81;
  --brand-dark: #2f6fba;
  --java-blue: #2f6fba;
  --accent: #a8895f;
  --accent-soft: #f5ead2;
  --success: #3f8f62;
  --danger: #b85b4d;
  --code-bg: #fff9ed;
  --code-text: #2b2b29;
  --shadow: 0 24px 70px rgba(48, 37, 20, 0.18);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    "Microsoft YaHei", sans-serif;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --page-bg: #050505;
  --app-bg: #171817;
  --panel: #20211f;
  --panel-soft: #24231f;
  --rail: #28251f;
  --line: #39352d;
  --line-strong: #62553e;
  --text: #f5f1e8;
  --muted: #b8ad9b;
  --faint: #766e62;
  --brand: #8fbca9;
  --brand-dark: #72a8ee;
  --java-blue: #72a8ee;
  --accent: #d9b86a;
  --accent-soft: #302719;
  --success: #7bd49a;
  --danger: #ff8f80;
  --code-bg: #181818;
  --code-text: #f6efe2;
  --shadow: 0 18px 48px rgba(0, 0, 0, 0.35);
}

* {
  box-sizing: border-box;
}

html,
body {
  width: 100%;
  height: 100%;
  margin: 0;
  overflow: hidden;
}

body {
  min-width: 1120px;
  background: var(--page-bg);
  color: var(--text);
}

button,
textarea {
  font: inherit;
}

button {
  color: inherit;
}

a {
  color: var(--brand-dark);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.training-app {
  display: grid;
  grid-template-rows: 82px minmax(0, 1fr);
  width: calc(100vw - 14px);
  height: calc(100vh - 14px);
  margin: 7px;
  overflow: hidden;
  border: 1px solid color-mix(in srgb, var(--line) 86%, transparent);
  border-radius: 14px;
  background:
    linear-gradient(135deg, color-mix(in srgb, var(--java-blue) 4%, transparent), transparent 28%),
    var(--app-bg);
  box-shadow: var(--shadow);
}

.app-header {
  display: grid;
  grid-template-columns: 280px minmax(320px, 1fr) auto;
  gap: 18px;
  align-items: center;
  padding: 12px 20px;
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--panel) 94%, transparent);
}

.brand {
  display: flex;
  gap: 12px;
  align-items: center;
  min-width: 0;
}

.brand .brand-badge {
  position: relative;
  display: grid;
  flex: 0 0 44px;
  width: 44px;
  height: 44px;
  margin-top: 0;
  place-items: center;
  border: 1px solid color-mix(in srgb, var(--java-blue) 38%, var(--line));
  border-radius: 12px;
  background:
    linear-gradient(145deg, color-mix(in srgb, var(--java-blue) 14%, var(--panel)), color-mix(in srgb, var(--brand) 12%, var(--panel))),
    var(--panel);
  color: var(--java-blue);
  font-size: initial;
  box-shadow: 0 10px 22px rgba(47, 111, 186, 0.14);
}

.brand-badge::after {
  position: absolute;
  right: 6px;
  bottom: 5px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--brand);
  content: "";
}

.brand .brand-letter {
  display: block;
  margin: 0;
  color: var(--java-blue);
  font-size: 1.42rem;
  font-weight: 950;
  line-height: 1;
  transform: translateY(-1px);
}

.brand strong {
  display: block;
  overflow: hidden;
  font-size: 1.18rem;
  line-height: 1.15;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.brand span {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-size: 0.74rem;
}

.brand > div {
  min-width: 0;
}

.progress-hub {
  display: grid;
  grid-template-columns: auto minmax(240px, 520px) 48px;
  gap: 14px;
  align-items: center;
  justify-content: center;
  color: var(--brand-dark);
  font-size: 0.86rem;
}

.progress-hub strong,
.progress-hub b {
  white-space: nowrap;
}

.progress-track {
  height: 10px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #efe7da;
}

:root[data-theme="dark"] .progress-track {
  background: #1f1d19;
}

.progress-track span {
  display: block;
  width: 0%;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--accent), var(--brand));
}

.header-actions {
  display: flex;
  gap: 8px;
}

.square-button,
.soft-button,
.run-button,
.link-button,
.submit-button,
.next-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: 1px solid var(--line);
  border-radius: 10px;
  cursor: pointer;
  transition:
    transform 150ms ease,
    border-color 150ms ease,
    background 150ms ease;
}

.square-button:hover,
.soft-button:hover,
.run-button:hover,
.submit-button:hover,
.next-button:hover {
  transform: translateY(-1px);
  border-color: var(--line-strong);
}

.square-button:disabled,
.soft-button:disabled,
.run-button:disabled,
.submit-button:disabled,
.next-button:disabled {
  cursor: not-allowed;
  opacity: 0.45;
  transform: none;
}

.square-button {
  width: 44px;
  height: 44px;
  background: var(--accent-soft);
  color: var(--brand-dark);
}

.square-button svg {
  width: 22px;
  height: 22px;
}

.button-glyph,
.tool-mark {
  display: inline-grid;
  place-items: center;
  line-height: 1;
  font-weight: 900;
}

.button-glyph {
  min-width: 1em;
  font-size: 1rem;
}

.square-button .button-glyph {
  font-size: 1.25rem;
}

.tool-mark {
  min-width: 24px;
  height: 24px;
  border: 1px solid color-mix(in srgb, var(--line) 78%, transparent);
  border-radius: 7px;
  color: var(--java-blue);
  font: 0.72rem/1 "Cascadia Code", Consolas, monospace;
  background: color-mix(in srgb, var(--java-blue) 7%, var(--panel));
}

.study-grid {
  display: grid;
  grid-template-columns: 202px minmax(390px, 0.68fr) minmax(610px, 1.32fr);
  gap: 10px;
  min-height: 0;
  padding: 10px 12px 12px;
  background: transparent;
}

.level-sidebar {
  min-height: 0;
  overflow-y: auto;
  border: 1px solid color-mix(in srgb, var(--line) 88%, transparent);
  border-radius: 12px;
  background: color-mix(in srgb, var(--panel) 88%, transparent);
  scrollbar-color: var(--line-strong) transparent;
}

.level-list {
  padding: 8px 0 18px;
}

.level-group-title {
  position: sticky;
  top: 0;
  z-index: 2;
  padding: 10px 12px 8px;
  background: color-mix(in srgb, var(--panel) 92%, transparent);
  color: color-mix(in srgb, var(--text) 68%, var(--muted));
  font-size: 0.72rem;
  font-weight: 850;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.level-item {
  display: grid;
  grid-template-columns: 28px minmax(0, 1fr);
  gap: 9px;
  align-items: center;
  width: calc(100% - 14px);
  min-height: 50px;
  margin: 2px 7px;
  padding: 7px 9px;
  border: 1px solid transparent;
  border-radius: 8px;
  background: transparent;
  color: color-mix(in srgb, var(--text) 64%, var(--muted));
  text-align: left;
}

.lesson-index {
  display: grid;
  width: 28px;
  height: 28px;
  place-items: center;
  border: 1px solid color-mix(in srgb, var(--line) 76%, transparent);
  border-radius: 8px;
  background: color-mix(in srgb, var(--java-blue) 6%, var(--panel));
  color: color-mix(in srgb, var(--java-blue) 76%, var(--muted));
  font: 0.7rem/1 "Cascadia Code", Consolas, monospace;
  font-weight: 850;
}

.level-copy {
  display: block;
  min-width: 0;
}

.level-item strong {
  display: block;
  overflow: hidden;
  font-size: 0.76rem;
  line-height: 1.22;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.level-subtitle {
  display: block;
  min-width: 0;
  overflow: hidden;
  margin-top: 2px;
  color: var(--faint);
  font-size: 0.64rem;
  line-height: 1.2;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.level-item.is-active {
  border-color: color-mix(in srgb, var(--java-blue) 24%, var(--line));
  background:
    linear-gradient(90deg, color-mix(in srgb, var(--java-blue) 10%, transparent), transparent 88%),
    var(--panel-soft);
  color: color-mix(in srgb, var(--text) 78%, var(--brand-dark));
}

.level-item.is-active .lesson-index {
  background: color-mix(in srgb, var(--java-blue) 15%, var(--panel));
  color: var(--java-blue);
}

.level-item.is-completed .lesson-index {
  border-color: color-mix(in srgb, var(--success) 34%, var(--line));
  background: color-mix(in srgb, var(--success) 9%, var(--panel));
  color: var(--success);
}

.level-item.is-locked {
  cursor: not-allowed;
  opacity: 0.48;
}

.level-item.is-locked .lesson-index {
  border-color: color-mix(in srgb, var(--faint) 28%, var(--line));
  background: color-mix(in srgb, var(--faint) 8%, var(--panel));
  color: var(--faint);
}

.level-item.is-locked strong,
.level-item.is-locked .level-subtitle {
  color: var(--faint);
}

.lesson-status {
  display: none;
}

.lesson-column {
  min-width: 0;
  min-height: 0;
  overflow-y: auto;
  border: 1px solid color-mix(in srgb, var(--line) 88%, transparent);
  border-radius: 12px;
  background: color-mix(in srgb, var(--panel) 96%, transparent);
  scrollbar-color: var(--line-strong) transparent;
}

.level-sidebar::-webkit-scrollbar,
.lesson-column::-webkit-scrollbar,
#consoleOutput::-webkit-scrollbar,
#focusOutput::-webkit-scrollbar {
  width: 10px;
}

.level-sidebar::-webkit-scrollbar-track,
.lesson-column::-webkit-scrollbar-track,
#consoleOutput::-webkit-scrollbar-track,
#focusOutput::-webkit-scrollbar-track {
  background: transparent;
}

.level-sidebar::-webkit-scrollbar-thumb,
.lesson-column::-webkit-scrollbar-thumb,
#consoleOutput::-webkit-scrollbar-thumb,
#focusOutput::-webkit-scrollbar-thumb {
  border: 3px solid transparent;
  border-radius: 999px;
  background: color-mix(in srgb, var(--line-strong) 80%, transparent);
  background-clip: padding-box;
}

.lesson-article {
  max-width: 620px;
  margin: 0 auto;
  padding: 30px 30px 64px;
}

.lesson-article h1 {
  margin: 0 0 20px;
  font-size: clamp(1.42rem, 1.55vw, 1.78rem);
  line-height: 1.16;
}

.lesson-article h2 {
  margin: 22px 0 14px;
  font-size: clamp(1.22rem, 1.35vw, 1.55rem);
  line-height: 1.25;
}

.lesson-article h3 {
  margin: 24px 0 10px;
  color: var(--brand-dark);
  font-size: 1rem;
}

.lesson-article p,
.lesson-article li {
  font-size: 0.9rem;
  line-height: 1.7;
}

.lesson-article p {
  margin: 12px 0;
}

.lesson-article ul {
  margin: 12px 0 0;
  padding-left: 1.4rem;
}

.lesson-article li + li {
  margin-top: 6px;
}

.code-pill {
  display: inline-flex;
  padding: 1px 6px;
  border: 1px solid color-mix(in srgb, var(--line-strong) 72%, var(--line));
  border-radius: 6px;
  background: var(--code-bg);
  color: var(--brand-dark);
  font-family: "Cascadia Code", "Fira Code", Consolas, monospace;
}

.example-box,
.task-box,
.source-box {
  margin: 12px 0 20px;
  padding: 13px 16px;
  border: 1px solid color-mix(in srgb, var(--line-strong) 72%, var(--line));
  border-radius: 10px;
  background: var(--code-bg);
}

.example-box pre {
  margin: 0;
  overflow: auto;
  color: var(--code-text);
  font: 0.9rem/1.55 "Cascadia Code", "Fira Code", Consolas, monospace;
}

.task-box {
  border-style: dashed;
  border-width: 2px;
  background: color-mix(in srgb, var(--accent-soft) 65%, var(--panel));
}

.task-label {
  display: inline-flex;
  transform: translateY(-32px);
  margin-bottom: -20px;
  padding: 8px 16px;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  background: var(--panel);
  color: var(--brand-dark);
  font-weight: 850;
}

.source-box a {
  display: block;
  margin-top: 8px;
  font-weight: 800;
}

.practice-column {
  display: grid;
  grid-template-rows: minmax(360px, 1.2fr) minmax(160px, 0.52fr) 54px;
  gap: 12px;
  min-width: 0;
  min-height: 0;
  padding: 14px;
  border: 1px solid color-mix(in srgb, var(--line) 88%, transparent);
  border-radius: 12px;
  background:
    linear-gradient(180deg, color-mix(in srgb, var(--java-blue) 5%, transparent), transparent 34%),
    color-mix(in srgb, var(--panel) 94%, transparent);
}

.editor-panel,
.console-panel {
  min-height: 0;
  overflow: hidden;
  border: 1px solid color-mix(in srgb, var(--line) 80%, transparent);
  border-radius: 10px;
  background: color-mix(in srgb, var(--panel) 96%, transparent);
}

.editor-panel {
  border-top: 3px solid color-mix(in srgb, var(--java-blue) 64%, var(--line));
}

.console-panel {
  border-top: 3px solid color-mix(in srgb, var(--brand) 54%, var(--line));
}

.panel-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  min-height: 46px;
  padding: 7px 14px;
  border-bottom: 1px solid color-mix(in srgb, var(--line) 64%, transparent);
  color: var(--muted);
  font-weight: 800;
}

.panel-toolbar span,
.panel-toolbar div {
  display: flex;
  align-items: center;
  gap: 10px;
  white-space: nowrap;
}

.panel-toolbar em {
  padding: 3px 7px;
  border: 1px solid color-mix(in srgb, var(--line) 75%, transparent);
  border-radius: 999px;
  color: var(--faint);
  font-style: normal;
  font-size: 0.68rem;
  font-weight: 850;
}

.panel-toolbar svg {
  width: 18px;
  height: 18px;
}

.soft-button,
.run-button {
  min-height: 32px;
  padding: 0 11px;
  font-weight: 800;
  white-space: nowrap;
  font-size: 0.8rem;
}

.soft-button {
  background: color-mix(in srgb, var(--panel) 80%, transparent);
  color: var(--brand-dark);
}

.run-button {
  border-color: color-mix(in srgb, var(--accent) 70%, var(--line));
  background: var(--brand);
  color: #fff;
}

#codeEditor {
  display: block;
  width: 100%;
  height: calc(100% - 46px);
  padding: 18px 20px;
  border: 0;
  outline: 0;
  resize: none;
  background: var(--code-bg);
  color: var(--code-text);
  font: 0.96rem/1.62 "Cascadia Code", "Fira Code", Consolas, monospace;
  tab-size: 4;
  overflow-x: hidden;
  white-space: pre-wrap;
  word-break: break-word;
}

.console-panel {
  position: relative;
}

.link-button {
  min-height: 34px;
  padding: 0 4px;
  border: 0;
  background: transparent;
  color: var(--faint);
}

#consoleOutput {
  width: 100%;
  height: calc(100% - 46px);
  margin: 0;
  overflow: auto;
  padding: 16px 20px;
  color: var(--code-text);
  font: 0.9rem/1.55 "Cascadia Code", "Fira Code", Consolas, monospace;
  white-space: pre-wrap;
}

.run-meta {
  position: absolute;
  right: 18px;
  bottom: 12px;
  color: var(--muted);
  font-size: 0.82rem;
}

.submit-button {
  width: 100%;
  min-height: 54px;
  border-color: color-mix(in srgb, var(--success) 35%, var(--line));
  background: color-mix(in srgb, var(--success) 9%, var(--panel));
  color: var(--success);
  font-size: 0.92rem;
  font-weight: 900;
}

.submit-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 10px;
  min-width: 0;
}

.next-button {
  min-height: 54px;
  padding: 0 16px;
  border: 1px solid color-mix(in srgb, var(--java-blue) 36%, var(--line));
  border-radius: 10px;
  background: color-mix(in srgb, var(--java-blue) 9%, var(--panel));
  color: var(--java-blue);
  cursor: pointer;
  font-weight: 900;
  white-space: nowrap;
}

.next-button:hover {
  transform: translateY(-1px);
  border-color: color-mix(in srgb, var(--java-blue) 52%, var(--line));
}

.next-button:disabled,
.next-button[hidden] {
  display: none;
}

.status-success {
  color: var(--success);
}

.status-error {
  color: var(--danger);
}

.status-warn {
  color: var(--brand-dark);
}

.answer-drawer {
  position: fixed;
  z-index: 50;
  top: 100px;
  bottom: 20px;
  left: 20px;
  display: grid;
  grid-template-rows: auto minmax(0, 1fr);
  width: calc(100vw - 700px);
  min-width: 500px;
  max-width: 570px;
  overflow: hidden;
  border: 1px solid color-mix(in srgb, var(--line-strong) 70%, var(--line));
  border-radius: 12px;
  background: var(--panel);
  box-shadow: 0 24px 70px rgba(58, 43, 22, 0.22);
  opacity: 0;
  pointer-events: none;
  transform: translateX(-20px);
  transition:
    opacity 160ms ease,
    transform 160ms ease;
}

.answer-drawer.is-open {
  opacity: 1;
  pointer-events: auto;
  transform: translateX(0);
}

.answer-drawer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px;
  border-bottom: 1px solid var(--line);
  background:
    linear-gradient(135deg, color-mix(in srgb, var(--java-blue) 7%, transparent), transparent 70%),
    var(--panel-soft);
}

.answer-drawer-header strong,
.answer-drawer-header span {
  display: block;
}

.answer-drawer-header strong {
  font-size: inherit;
}

.answer-drawer-header span {
  margin-top: 3px;
  color: var(--muted);
}

.answer-drawer-body {
  min-height: 0;
  overflow: auto;
  padding: 16px;
}

.answer-drawer-body p {
  margin: 0 0 12px;
  color: var(--muted);
  font-size: 0.88rem;
  line-height: 1.65;
}

.answer-drawer-body code {
  font-family: "Cascadia Code", "Fira Code", Consolas, monospace;
}

.answer-drawer-body pre {
  margin: 12px 0;
  overflow: auto;
  overflow-x: hidden;
  padding: 18px 20px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--code-bg);
  color: var(--code-text);
  font: 0.9rem/1.58 "Cascadia Code", "Fira Code", Consolas, monospace;
  white-space: pre-wrap;
  word-break: break-word;
}

.focus-modal {
  position: fixed;
  inset: 0;
  z-index: 80;
  display: none;
  padding: 28px;
  background: rgba(0, 0, 0, 0.54);
  backdrop-filter: blur(12px);
}

.focus-modal.is-open {
  display: grid;
  place-items: center;
}

.focus-dialog {
  display: grid;
  grid-template-rows: 68px minmax(0, 1fr);
  width: min(1440px, 94vw);
  height: min(880px, 90vh);
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--panel);
  box-shadow: 0 26px 70px rgba(0, 0, 0, 0.42);
}

.focus-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 12px 18px;
  border-bottom: 1px solid var(--line);
  background: var(--panel-soft);
}

.focus-header strong,
.focus-header span {
  display: block;
}

.focus-header strong {
  font-size: 1.05rem;
}

.focus-header span {
  margin-top: 3px;
  color: var(--muted);
  font-size: 0.82rem;
}

.focus-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.square-button.compact {
  width: 38px;
  height: 38px;
  border-radius: 8px;
}

.focus-body {
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(340px, 0.75fr);
  gap: 12px;
  min-height: 0;
  padding: 12px;
  background: var(--app-bg);
}

#focusEditor {
  width: 100%;
  height: 100%;
  min-height: 0;
  overflow-x: hidden;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 10px;
  outline: 0;
  resize: none;
  background: var(--code-bg);
  color: var(--code-text);
  font: 1rem/1.65 "Cascadia Code", "Fira Code", Consolas, monospace;
  tab-size: 4;
  white-space: pre-wrap;
  word-break: break-word;
}

.focus-console {
  display: grid;
  grid-template-rows: 44px minmax(0, 1fr);
  min-width: 0;
  min-height: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--code-bg);
}

.focus-console-title {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 10px 14px;
  border-bottom: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.84rem;
  font-weight: 800;
}

#focusOutput {
  min-height: 0;
  margin: 0;
  overflow: auto;
  padding: 18px;
  color: var(--code-text);
  font: 0.92rem/1.55 "Cascadia Code", "Fira Code", Consolas, monospace;
  white-space: pre-wrap;
  word-break: break-word;
}

@media (max-width: 1360px) {
  body {
    min-width: 1120px;
  }

  .app-header {
    grid-template-columns: 260px minmax(260px, 1fr) auto;
    padding: 12px 18px;
  }

  .brand .brand-badge {
    width: 44px;
    height: 44px;
    flex-basis: 44px;
  }

  .brand strong {
    font-size: 1.16rem;
  }

  .progress-hub {
    grid-template-columns: auto minmax(170px, 420px) 42px;
    gap: 10px;
    font-size: 0.82rem;
  }

  .header-actions {
    gap: 8px;
  }

  .square-button {
    width: 44px;
    height: 44px;
  }

  .study-grid {
    grid-template-columns: 196px minmax(380px, 0.65fr) minmax(600px, 1.35fr);
  }

  .lesson-article {
    padding: 28px 28px 56px;
  }

  .lesson-article p,
  .lesson-article li {
    font-size: 0.9rem;
    line-height: 1.68;
  }

  .lesson-article h1 {
    font-size: 1.55rem;
  }

  .lesson-article h2 {
    font-size: 1.25rem;
  }

  .practice-column {
    grid-template-rows: minmax(300px, 1fr) minmax(150px, 0.58fr) 54px;
    gap: 12px;
    padding: 14px;
  }

  .panel-toolbar {
    min-height: 46px;
    padding: 7px 14px;
  }

  .soft-button,
  .run-button {
    min-height: 32px;
    padding: 0 11px;
  }

  #codeEditor,
  #consoleOutput {
    height: calc(100% - 46px);
    padding: 16px 20px;
    font-size: 0.92rem;
  }

  .submit-button {
    min-height: 54px;
  }
}

/* Studio UI pass: make the editor the stage, keep navigation quiet. */
:root {
  --page-bg: #111312;
  --app-bg: #f3ede4;
  --panel: #fffaf2;
  --panel-soft: #f8f1e8;
  --rail: #ebe1d3;
  --line: #ded1bd;
  --line-strong: #b99b6d;
  --text: #171a1d;
  --muted: #6e675e;
  --faint: #9b9286;
  --brand: #547f6e;
  --brand-dark: #2467b6;
  --java-blue: #2467b6;
  --accent: #b98748;
  --accent-soft: #f2e7d4;
  --code-bg: #fff7e8;
  --code-text: #181c20;
  --shadow: 0 22px 58px rgba(25, 22, 16, 0.22);
}

:root[data-theme="dark"] {
  --page-bg: #050608;
  --app-bg: #101214;
  --panel: #171a1d;
  --panel-soft: #1d2024;
  --rail: #15181b;
  --line: #2d3339;
  --line-strong: #53606a;
  --text: #f3f0e8;
  --muted: #b0aa9f;
  --faint: #777166;
  --brand: #7bb79e;
  --brand-dark: #7db8ff;
  --java-blue: #7db8ff;
  --accent: #d0a15e;
  --accent-soft: #272018;
  --code-bg: #111315;
  --code-text: #f3eadc;
  --shadow: 0 22px 58px rgba(0, 0, 0, 0.5);
}

body {
  background: var(--page-bg);
}

.training-app {
  grid-template-rows: 70px minmax(0, 1fr);
  width: calc(100vw - 16px);
  height: calc(100vh - 16px);
  margin: 8px;
  border-radius: 12px;
  background: var(--app-bg);
  box-shadow: var(--shadow);
}

.app-header {
  grid-template-columns: 270px minmax(280px, 1fr) auto;
  gap: 16px;
  padding: 10px 18px;
  border-bottom-color: color-mix(in srgb, var(--line) 74%, transparent);
  background: color-mix(in srgb, var(--panel) 92%, transparent);
}

.brand {
  gap: 10px;
}

.brand .brand-badge {
  flex-basis: 38px;
  width: 38px;
  height: 38px;
  border-radius: 8px;
  border-color: color-mix(in srgb, var(--java-blue) 38%, var(--line));
  background:
    linear-gradient(135deg, color-mix(in srgb, var(--java-blue) 20%, var(--panel)) 0 50%, color-mix(in srgb, var(--brand) 16%, var(--panel)) 50% 100%);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.58),
    0 8px 18px rgba(36, 103, 182, 0.13);
}

.brand-badge::after {
  right: 5px;
  bottom: 5px;
  width: 6px;
  height: 6px;
  border: 1px solid color-mix(in srgb, var(--panel) 70%, transparent);
  background: var(--brand);
}

.brand .brand-letter {
  font-size: 1.28rem;
  letter-spacing: 0;
}

.brand strong {
  font-size: 1.02rem;
  line-height: 1.1;
}

.brand span {
  margin-top: 2px;
  font-size: 0.68rem;
}

.progress-hub {
  grid-template-columns: auto minmax(180px, 520px) 42px;
  gap: 12px;
  color: color-mix(in srgb, var(--text) 62%, var(--java-blue));
  font-size: 0.78rem;
}

.progress-track {
  height: 7px;
  border: 0;
  background: color-mix(in srgb, var(--line) 46%, var(--panel-soft));
}

.header-actions {
  gap: 7px;
}

.square-button {
  width: 38px;
  height: 38px;
  border-radius: 8px;
  background: color-mix(in srgb, var(--panel) 84%, var(--accent-soft));
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.45);
}

.square-button .button-glyph {
  font-size: 1.05rem;
}

.study-grid {
  grid-template-columns: 186px minmax(330px, 0.58fr) minmax(640px, 1.42fr);
  gap: 10px;
  padding: 10px;
}

.level-sidebar,
.lesson-column,
.practice-column,
.editor-panel,
.console-panel,
.focus-dialog,
.focus-console,
#focusEditor,
.answer-drawer {
  border-radius: 8px;
}

.level-sidebar {
  border-color: color-mix(in srgb, var(--line) 66%, transparent);
  background: color-mix(in srgb, var(--rail) 58%, var(--panel));
}

.level-list {
  padding: 7px 0 12px;
}

.level-group-title {
  padding: 12px 12px 7px;
  background: color-mix(in srgb, var(--rail) 72%, var(--panel));
  color: color-mix(in srgb, var(--text) 72%, var(--muted));
  font-size: 0.66rem;
  letter-spacing: 0;
  text-transform: uppercase;
}

.level-item {
  grid-template-columns: 26px minmax(0, 1fr);
  gap: 8px;
  width: calc(100% - 12px);
  min-height: 45px;
  margin: 2px 6px;
  padding: 6px 7px;
  border-radius: 7px;
}

.lesson-index {
  width: 26px;
  height: 26px;
  border-radius: 7px;
  background: color-mix(in srgb, var(--panel) 82%, var(--java-blue));
  color: var(--java-blue);
  font-size: 0.65rem;
}

.level-item strong {
  font-size: 0.72rem;
  line-height: 1.16;
}

.level-subtitle {
  margin-top: 2px;
  font-size: 0.6rem;
  line-height: 1.14;
}

.level-item.is-active {
  border-color: color-mix(in srgb, var(--java-blue) 36%, var(--line));
  background:
    linear-gradient(90deg, color-mix(in srgb, var(--java-blue) 14%, transparent), transparent 92%),
    color-mix(in srgb, var(--panel) 88%, var(--rail));
  box-shadow: inset 3px 0 0 var(--java-blue);
}

.level-item.is-active .lesson-index {
  border-color: color-mix(in srgb, var(--java-blue) 40%, var(--line));
  background: color-mix(in srgb, var(--java-blue) 13%, var(--panel));
}

.lesson-column {
  border-color: color-mix(in srgb, var(--line) 62%, transparent);
  background: color-mix(in srgb, var(--panel) 88%, transparent);
}

.lesson-article {
  max-width: 560px;
  padding: 24px 22px 50px;
}

.lesson-article h1 {
  margin-bottom: 16px;
  font-size: 1.24rem;
  letter-spacing: 0;
}

.lesson-article h2 {
  margin: 18px 0 12px;
  font-size: 1rem;
  letter-spacing: 0;
}

.lesson-article h3 {
  margin: 20px 0 8px;
  font-size: 0.9rem;
}

.lesson-article p,
.lesson-article li {
  font-size: 0.84rem;
  line-height: 1.67;
}

.example-box,
.task-box,
.source-box {
  border-radius: 8px;
  padding: 12px 14px;
  background: color-mix(in srgb, var(--code-bg) 82%, var(--panel));
}

.task-label {
  padding: 6px 12px;
  transform: translateY(-27px);
  margin-bottom: -17px;
  border-radius: 999px;
  font-size: 0.78rem;
}

.practice-column {
  grid-template-rows: minmax(380px, 1.38fr) minmax(148px, 0.42fr) 48px;
  gap: 10px;
  padding: 14px;
  border-color: color-mix(in srgb, var(--java-blue) 24%, var(--line));
  background:
    linear-gradient(180deg, color-mix(in srgb, var(--java-blue) 8%, transparent), transparent 34%),
    color-mix(in srgb, var(--panel) 94%, transparent);
  box-shadow: inset 0 1px 0 color-mix(in srgb, #fff 55%, transparent);
}

:root[data-theme="dark"] .practice-column {
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.04);
}

.editor-panel,
.console-panel {
  border-color: color-mix(in srgb, var(--line) 62%, transparent);
  background: var(--code-bg);
}

.editor-panel {
  border-top: 0;
  box-shadow:
    inset 0 3px 0 var(--java-blue),
    0 16px 28px rgba(36, 103, 182, 0.07);
}

.console-panel {
  border-top: 0;
  box-shadow: inset 0 3px 0 color-mix(in srgb, var(--brand) 78%, var(--line));
}

.panel-toolbar {
  min-height: 42px;
  padding: 6px 12px;
  border-bottom-color: color-mix(in srgb, var(--line) 62%, transparent);
  background: color-mix(in srgb, var(--panel) 78%, transparent);
  font-size: 0.82rem;
}

.tool-mark {
  min-width: 22px;
  height: 22px;
  border-radius: 6px;
  font-size: 0.66rem;
}

.panel-toolbar em {
  padding: 2px 6px;
  font-size: 0.63rem;
}

.soft-button,
.run-button {
  min-height: 30px;
  border-radius: 8px;
  padding: 0 10px;
  font-size: 0.75rem;
}

.soft-button.is-active {
  border-color: color-mix(in srgb, var(--java-blue) 52%, var(--line));
  background: color-mix(in srgb, var(--java-blue) 12%, var(--panel));
  color: var(--java-blue);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--java-blue) 12%, transparent);
}

.run-button {
  background: linear-gradient(180deg, color-mix(in srgb, var(--brand) 92%, #fff), var(--brand));
  box-shadow: 0 8px 16px color-mix(in srgb, var(--brand) 20%, transparent);
}

#codeEditor {
  height: calc(100% - 42px);
  padding: 20px 22px;
  font-size: 0.95rem;
  line-height: 1.68;
  background:
    linear-gradient(90deg, color-mix(in srgb, var(--line) 24%, transparent) 1px, transparent 1px) 52px 0 / 1px 100% no-repeat,
    var(--code-bg);
}

#consoleOutput {
  height: calc(100% - 42px);
  padding: 15px 20px;
  font-size: 0.86rem;
}

.run-meta {
  right: 16px;
  bottom: 10px;
  font-size: 0.74rem;
}

.submit-button {
  min-height: 48px;
  border-radius: 8px;
  background:
    linear-gradient(180deg, color-mix(in srgb, var(--success) 12%, var(--panel)), color-mix(in srgb, var(--success) 6%, var(--panel)));
  font-size: 0.84rem;
}

.next-button {
  min-height: 48px;
  border-radius: 8px;
  padding: 0 14px;
  font-size: 0.84rem;
}

.answer-drawer {
  top: 88px;
  left: var(--answer-drawer-left, 18px);
  right: var(--answer-drawer-right, calc(100vw - 560px));
  bottom: 18px;
  width: auto;
  min-width: 0;
  max-width: none;
  border-color: color-mix(in srgb, var(--java-blue) 22%, var(--line));
  box-shadow: 0 22px 54px rgba(25, 22, 16, 0.24);
}

.answer-drawer-header {
  padding: 12px 14px;
}

.answer-drawer-body {
  padding: 14px;
}

.focus-dialog {
  width: min(1480px, 95vw);
  height: min(900px, 92vh);
}

.focus-header {
  background: color-mix(in srgb, var(--panel) 88%, var(--panel-soft));
}

.focus-body {
  grid-template-columns: minmax(0, 1.45fr) minmax(320px, 0.55fr);
  background: var(--app-bg);
}

#focusEditor {
  border-radius: 8px;
  font-size: 0.98rem;
}

.code-surface {
  display: grid;
  grid-template-columns: 52px minmax(0, 1fr);
  height: calc(100% - 42px);
  min-height: 0;
  overflow: hidden;
  background: var(--code-bg);
}

.editor-lines {
  height: 100%;
  margin: 0;
  overflow: hidden;
  padding: 20px 10px 20px 0;
  border-right: 1px solid color-mix(in srgb, var(--line) 42%, transparent);
  background: color-mix(in srgb, var(--panel) 26%, transparent);
  color: color-mix(in srgb, var(--faint) 80%, transparent);
  font: 0.95rem/1.68 "Cascadia Code", "Fira Code", Consolas, monospace;
  text-align: right;
  user-select: none;
}

#codeEditor {
  height: 100%;
  padding: 20px 22px 20px 18px;
  background: var(--code-bg);
}

.focus-code-surface {
  height: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
}

.focus-code-surface .editor-lines {
  padding-top: 24px;
  font-size: 0.98rem;
  line-height: 1.65;
}

#focusEditor {
  height: 100%;
  padding: 24px 24px 24px 18px;
  border: 0;
  border-radius: 0;
  background: var(--code-bg);
}

@media (max-width: 1360px) {
  .app-header {
    grid-template-columns: 250px minmax(230px, 1fr) auto;
    padding: 10px 16px;
  }

  .study-grid {
    grid-template-columns: 178px minmax(310px, 0.55fr) minmax(600px, 1.45fr);
    gap: 9px;
  }

  .lesson-article {
    padding: 22px 20px 46px;
  }

  .practice-column {
    grid-template-rows: minmax(340px, 1.35fr) minmax(142px, 0.44fr) 48px;
    padding: 12px;
  }

  .soft-button,
  .run-button {
    padding: 0 9px;
  }
}

@media (max-width: 980px) {
  html,
  body {
    height: auto;
    min-height: 100%;
    overflow-x: hidden;
    overflow-y: auto;
  }

  body {
    min-width: 0;
  }

  .training-app {
    grid-template-rows: auto minmax(0, 1fr);
    width: calc(100vw - 12px);
    height: auto;
    min-height: calc(100vh - 12px);
    margin: 6px;
    overflow: visible;
  }

  .app-header {
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 10px 12px;
    padding: 10px 12px;
  }

  .brand strong {
    font-size: 0.96rem;
  }

  .progress-hub {
    grid-column: 1 / -1;
    grid-template-columns: auto minmax(0, 1fr) auto;
    justify-content: stretch;
    width: 100%;
  }

  .progress-track {
    min-width: 0;
  }

  .study-grid {
    grid-template-columns: minmax(0, 1fr);
    gap: 10px;
    padding: 10px;
  }

  .level-sidebar {
    max-height: 238px;
  }

  .lesson-column {
    overflow: visible;
  }

  .lesson-article {
    max-width: none;
  }

  .practice-column {
    grid-template-rows: minmax(320px, 42vh) minmax(150px, 24vh) 48px;
  }

  .answer-drawer {
    top: 82px;
    right: 12px;
    bottom: 12px;
    left: 12px;
  }

  .focus-modal {
    padding: 10px;
  }

  .focus-dialog {
    width: 100%;
    height: 100%;
  }

  .focus-body {
    grid-template-columns: minmax(0, 1fr);
    grid-template-rows: minmax(0, 1.25fr) minmax(180px, 0.75fr);
  }
}

@media (max-width: 560px) {
  .training-app {
    width: calc(100vw - 8px);
    min-height: calc(100vh - 8px);
    margin: 4px;
    border-radius: 10px;
  }

  .app-header {
    padding: 9px 10px;
  }

  .brand {
    gap: 8px;
  }

  .brand .brand-badge {
    flex-basis: 34px;
    width: 34px;
    height: 34px;
  }

  .brand strong {
    font-size: 0.9rem;
  }

  .brand span {
    font-size: 0.62rem;
  }

  .square-button {
    width: 34px;
    height: 34px;
  }

  .progress-hub {
    grid-template-columns: 1fr auto;
    gap: 7px 9px;
    font-size: 0.72rem;
  }

  .progress-track {
    grid-column: 1 / -1;
    grid-row: 2;
  }

  .study-grid {
    padding: 8px;
  }

  .level-sidebar {
    max-height: 214px;
  }

  .lesson-article {
    padding: 20px 16px 36px;
  }

  .lesson-article h1 {
    font-size: 1.12rem;
  }

  .lesson-article h2 {
    font-size: 0.96rem;
  }

  .lesson-article p,
  .lesson-article li {
    font-size: 0.82rem;
  }

  .practice-column {
    grid-template-rows: minmax(300px, 48vh) minmax(150px, 26vh) 48px;
    padding: 9px;
  }

  .panel-toolbar {
    flex-wrap: wrap;
    gap: 8px;
    min-height: auto;
  }

  .panel-toolbar span,
  .panel-toolbar div {
    flex-wrap: wrap;
    min-width: 0;
  }

  .soft-button,
  .run-button {
    padding: 0 8px;
  }

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

  .next-button {
    width: 100%;
  }

  .code-surface {
    grid-template-columns: 42px minmax(0, 1fr);
  }

  .editor-lines,
  .focus-code-surface .editor-lines {
    padding-top: 16px;
    font-size: 0.82rem;
  }

  #codeEditor,
  #focusEditor {
    padding: 16px 14px;
    font-size: 0.84rem;
  }

  #consoleOutput,
  #focusOutput {
    padding: 13px 14px;
    font-size: 0.8rem;
  }

  .focus-dialog {
    grid-template-rows: auto minmax(0, 1fr);
  }

  .focus-header {
    flex-wrap: wrap;
  }
}