:root {
  color-scheme: light;
  --paper: #f5f7fb;
  --card: #ffffff;
  --ink: #172033;
  --muted: #647086;
  --line: #dce2ec;
  --blue: #3157d5;
  --blue-soft: #e9efff;
  --green: #157a5b;
  --green-soft: #e9f8f1;
  --red: #bc4039;
  --red-soft: #fff0ef;
  --amber: #9b6507;
  --amber-soft: #fff6df;
  --shadow: 0 18px 55px rgba(28, 39, 67, 0.1);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background:
    radial-gradient(circle at 10% 0, #e7eeff 0, transparent 28rem),
    var(--paper);
  color: var(--ink);
  font-family: "Noto Sans SC", "Source Han Sans SC", "Microsoft YaHei", sans-serif;
  line-height: 1.7;
}

a {
  color: var(--blue);
}

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

.lab-shell {
  width: min(980px, calc(100% - 32px));
  margin: 0 auto;
  padding: 24px 0 56px;
}

.lab-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 28px;
}

.lab-topbar a {
  color: var(--ink);
  font-weight: 700;
  text-decoration: none;
}

.lab-kicker {
  display: inline-block;
  margin-bottom: 10px;
  color: var(--blue);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.08em;
}

h1 {
  max-width: 760px;
  margin: 0;
  font-size: clamp(2rem, 6vw, 4rem);
  line-height: 1.12;
  letter-spacing: -0.04em;
  font-family: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;
}

h2 {
  margin: 0 0 14px;
  font-size: 1.25rem;
}

.lab-lead {
  max-width: 760px;
  margin: 18px 0 28px;
  color: var(--muted);
  font-size: 1.06rem;
}

.lab-meta,
.metric-grid,
.split-grid {
  display: grid;
  gap: 14px;
}

.lab-meta {
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin: 0 0 24px;
}

.lab-meta div,
.metric {
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.72);
}

.lab-meta strong,
.lab-meta span,
.metric strong,
.metric span {
  display: block;
}

.lab-meta strong,
.metric span {
  color: var(--muted);
  font-size: 0.78rem;
}

.panel {
  margin: 18px 0;
  padding: clamp(18px, 4vw, 30px);
  border: 1px solid var(--line);
  border-radius: 20px;
  background: var(--card);
  box-shadow: var(--shadow);
}

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

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

.metric strong {
  margin-top: 4px;
  font-size: 1.35rem;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 16px 0 0;
}

button,
.button-link {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  padding: 10px 16px;
  border: 1px solid transparent;
  border-radius: 10px;
  background: var(--blue);
  color: white;
  cursor: pointer;
  font-weight: 750;
  text-decoration: none;
}

button.secondary,
.button-link.secondary {
  border-color: var(--line);
  background: white;
  color: var(--ink);
}

button.ghost {
  border-color: var(--blue);
  background: transparent;
  color: var(--blue);
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.48;
}

button:focus-visible,
a:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
  outline: 3px solid rgba(49, 87, 213, 0.28);
  outline-offset: 2px;
}

.feedback {
  min-height: 56px;
  margin-top: 16px;
  padding: 12px 14px;
  border-radius: 12px;
  background: var(--blue-soft);
}

.feedback.success {
  background: var(--green-soft);
  color: #104a38;
}

.feedback.error {
  background: var(--red-soft);
  color: #6d211d;
}

.feedback.warn {
  background: var(--amber-soft);
  color: #593802;
}

.table-wrap {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
}

th,
td {
  padding: 11px 12px;
  border-bottom: 1px solid var(--line);
  text-align: left;
  white-space: nowrap;
}

th {
  color: var(--muted);
  font-size: 0.82rem;
}

tr.is-hidden td:not(:first-child) {
  color: transparent;
  user-select: none;
}

tr.is-hidden td:not(:first-child)::after {
  content: "尚未揭晓";
  color: #9ba5b7;
}

.question {
  padding: 16px;
  border-left: 4px solid var(--blue);
  border-radius: 10px;
  background: var(--blue-soft);
}

label {
  display: block;
  margin: 13px 0 5px;
  font-weight: 700;
}

input[type="text"],
input[type="number"],
select,
textarea {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 9px;
  background: white;
  color: var(--ink);
}

textarea {
  min-height: 90px;
  resize: vertical;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--blue);
}

.range-row {
  display: grid;
  grid-template-columns: 62px 1fr 70px;
  align-items: center;
  gap: 12px;
  margin: 8px 0;
}

.range-row output {
  text-align: right;
  font-variant-numeric: tabular-nums;
}

.chart {
  width: 100%;
  min-height: 260px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: linear-gradient(#fff, #fbfcff);
}

.sortable-list {
  display: grid;
  gap: 10px;
  padding: 0;
  list-style: none;
}

.sortable-item {
  display: grid;
  grid-template-columns: 42px 1fr auto;
  align-items: center;
  gap: 12px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: white;
}

.step-number {
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  border-radius: 50%;
  background: var(--blue-soft);
  color: var(--blue);
  font-weight: 800;
}

.move-buttons {
  display: flex;
  gap: 5px;
}

.move-buttons button {
  min-width: 36px;
  min-height: 36px;
  padding: 4px;
}

.code-block,
.preview {
  overflow: auto;
  padding: 16px;
  border-radius: 12px;
  background: #111827;
  color: #e7edf7;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 0.86rem;
  line-height: 1.65;
  white-space: pre-wrap;
}

.code-editor {
  min-height: 250px;
  border-color: #26344e;
  background: #111827;
  color: #e7edf7;
  font-family: "JetBrains Mono", "Cascadia Code", Consolas, monospace;
  line-height: 1.65;
  tab-size: 4;
}

.runtime-status {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 0.85rem;
}

.expected-output {
  margin-top: 14px;
  padding: 14px;
  border: 1px dashed var(--line);
  border-radius: 12px;
  background: #faf8f1;
}

.expected-output p {
  margin-bottom: 0;
}

.panel-heading-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.inline-label {
  margin: 0;
  color: var(--muted);
  font-size: 0.8rem;
}

.pipeline {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
  margin: 18px 0;
}

.pipeline button {
  min-width: 0;
  padding: 11px 8px;
  background: #172033;
  font-size: 0.82rem;
}

.code-lines {
  display: grid;
  gap: 6px;
  padding: 0;
  list-style: none;
}

.code-line-button {
  display: grid;
  width: 100%;
  grid-template-columns: 30px 1fr;
  justify-content: stretch;
  padding: 9px 10px;
  border-color: #28364e;
  background: #111827;
  color: #e7edf7;
  text-align: left;
}

.code-line-button code {
  overflow-wrap: anywhere;
  white-space: normal;
}

.code-line-button.active {
  border-color: #ef9b2d;
  box-shadow: 0 0 0 2px rgba(239, 155, 45, 0.22);
}

.stage-badge {
  display: inline-block;
  padding: 4px 9px;
  border-radius: 999px;
  background: var(--blue-soft);
  color: var(--blue);
  font-size: 0.75rem;
  font-weight: 800;
}

.explain-list {
  display: grid;
  grid-template-columns: 92px 1fr;
  gap: 10px 12px;
}

.explain-list dt {
  color: var(--muted);
  font-weight: 750;
}

.explain-list dd {
  margin: 0;
}

.order-book {
  display: grid;
  gap: 7px;
}

.order-book div {
  display: flex;
  justify-content: space-between;
  padding: 11px 13px;
  border-radius: 9px;
  background: var(--red-soft);
}

.fill-details {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 16px 0 0;
}

.fill-details span {
  padding: 7px 10px;
  border-radius: 999px;
  background: var(--blue-soft);
  font-size: 0.82rem;
}

.timeline-strip {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
}

.timeline-strip span {
  position: relative;
  padding: 12px 8px;
  border-radius: 10px;
  background: var(--blue-soft);
  text-align: center;
  font-size: 0.78rem;
}

.split-visual {
  display: flex;
  min-height: 86px;
  overflow: hidden;
  border-radius: 12px;
}

.split-visual span {
  display: grid;
  place-items: center;
  padding: 10px;
  text-align: center;
  font-size: 0.78rem;
}

.split-visual .train { flex: 3; background: #dbeafe; }
.split-visual .validate { flex: 1; background: #fef3c7; }
.split-visual .test { flex: 1; background: #dcfce7; }
.split-visual .mixed { flex: 1; background: repeating-linear-gradient(45deg, #dbeafe, #dbeafe 12px, #dcfce7 12px, #dcfce7 24px); }
.split-visual .mixed.alt { background: repeating-linear-gradient(-45deg, #fef3c7, #fef3c7 12px, #fee2e2 12px, #fee2e2 24px); }

.sequence-strip {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 6px;
  margin-top: 16px;
}

.sequence-strip span {
  display: flex;
  min-height: 72px;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: white;
}

.sequence-strip span.event {
  border-color: #e07a22;
  background: #fff1df;
  color: #7a3d05;
}

.sequence-strip span.today {
  border-color: var(--blue);
  background: var(--blue-soft);
}

.sequence-strip small {
  color: var(--muted);
  font-size: 0.65rem;
}

.memory-meter {
  height: 24px;
  overflow: hidden;
  border-radius: 999px;
  background: #e6eaf1;
}

.memory-meter span {
  display: block;
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, #e07a22, #3157d5);
  transition: width 240ms ease;
}

.big-number {
  display: block;
  margin: 16px 0 4px;
  font-family: "Noto Serif SC", "Source Han Serif SC", serif;
  font-size: 3rem;
}

.comparison-cards {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 10px;
  margin: 16px 0;
}

.comparison-cards article {
  padding: 13px;
  border: 1px solid var(--line);
  border-radius: 12px;
}

.comparison-cards strong,
.comparison-cards span {
  display: block;
}

.comparison-cards span {
  margin-top: 5px;
  color: var(--muted);
  font-size: 0.76rem;
}

.preview {
  min-height: 280px;
}

.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.chip {
  padding: 7px 11px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: white;
  color: var(--ink);
}

.lab-footer-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 26px;
}

.lab-footer-nav a {
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: white;
  color: var(--ink);
  text-decoration: none;
}

.lab-footer-nav a:last-child {
  text-align: right;
}

.lab-complete {
  width: 100%;
  margin-top: 14px;
  background: var(--green);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
}

@media (max-width: 720px) {
  .lab-meta,
  .metric-grid,
  .split-grid,
  .lab-footer-nav {
    grid-template-columns: 1fr;
  }

  .lab-footer-nav a:last-child {
    text-align: left;
  }

  .range-row {
    grid-template-columns: 52px 1fr 58px;
  }

  .sortable-item {
    grid-template-columns: 36px 1fr;
  }

  .move-buttons {
    grid-column: 2;
  }

  .pipeline,
  .timeline-strip,
  .comparison-cards {
    grid-template-columns: 1fr;
  }

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

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

  .explain-list dt {
    margin-top: 6px;
  }
}

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