:root {
  color-scheme: light;
  --canvas: #f4f6f3;
  --paper: #fffefd;
  --ink: #202522;
  --muted: #5d6862;
  --line: #cfd7d1;
  --target: #0b6b53;
  --target-soft: #e7f4ef;
  --draft: #8a5a00;
  --draft-soft: #fff3d6;
  --reject: #a33b32;
  --reject-soft: #faece9;
  --code: #edf0ed;
  --focus: #175d91;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--canvas);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 17px;
  line-height: 1.68;
}

main {
  width: min(100% - 32px, 1040px);
  margin: 0 auto;
  padding: 32px 0 72px;
}

header {
  padding: 16px 0 24px;
  border-bottom: 2px solid var(--ink);
  margin-bottom: 28px;
}

h1,
h2,
h3 {
  letter-spacing: 0;
  line-height: 1.25;
}

h1 {
  max-width: 860px;
  margin: 0 0 12px;
  font-size: 3.1rem;
}

h2 {
  margin: 40px 0 14px;
  font-size: 1.55rem;
}

h3 {
  margin: 20px 0 8px;
  font-size: 1.08rem;
}

p,
ul,
ol {
  margin: 10px 0;
}

a {
  color: var(--focus);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

code,
kbd {
  border-radius: 4px;
  background: var(--code);
  padding: 2px 5px;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 0.92em;
}

pre {
  overflow-x: auto;
  border-radius: 6px;
  background: #222824;
  color: #f5f7f5;
  padding: 16px;
  font-size: 0.88rem;
  line-height: 1.5;
}

pre code {
  background: transparent;
  padding: 0;
}

table {
  width: 100%;
  margin: 16px 0 24px;
  border-collapse: collapse;
  background: var(--paper);
  font-size: 0.94rem;
}

th,
td {
  border: 1px solid var(--line);
  padding: 10px 12px;
  text-align: left;
  vertical-align: top;
}

th {
  background: #e8ede9;
}

button,
input {
  font: inherit;
}

button {
  border: 1px solid var(--ink);
  border-radius: 6px;
  background: var(--paper);
  color: var(--ink);
  padding: 9px 12px;
  cursor: pointer;
}

button:hover,
button:focus-visible {
  border-color: var(--focus);
  outline: 2px solid transparent;
  box-shadow: 0 0 0 3px rgb(23 93 145 / 18%);
}

.subtitle {
  max-width: 820px;
  color: var(--muted);
  font-size: 1.06rem;
}

.meta,
.lesson-nav {
  color: var(--muted);
  font-size: 0.9rem;
}

.lesson-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  margin-top: 16px;
}

.callout,
.exercise,
.tool {
  margin: 20px 0;
  border: 1px solid var(--line);
  border-left: 5px solid var(--target);
  border-radius: 6px;
  background: var(--paper);
  padding: 16px 18px;
}

.callout.draft {
  border-left-color: var(--draft);
  background: var(--draft-soft);
}

.callout.reject {
  border-left-color: var(--reject);
  background: var(--reject-soft);
}

.formula {
  margin: 16px 0;
  overflow-x: auto;
  border-block: 1px solid var(--line);
  background: var(--paper);
  padding: 15px 18px;
  font-family: "Times New Roman", serif;
  font-size: 1.17rem;
  text-align: center;
  white-space: nowrap;
}

.pipeline {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 8px;
  margin: 20px 0;
}

.pipeline > div {
  min-height: 112px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--paper);
  padding: 12px;
}

.pipeline strong {
  display: block;
  margin-bottom: 5px;
}

.pipeline .draft-stage {
  border-top: 5px solid var(--draft);
}

.pipeline .target-stage {
  border-top: 5px solid var(--target);
}

.pipeline .reject-stage {
  border-top: 5px solid var(--reject);
}

.two-col,
.three-col {
  display: grid;
  gap: 16px;
}

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

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

.panel {
  border-top: 3px solid var(--ink);
  background: var(--paper);
  padding: 13px 14px;
}

.panel h3 {
  margin-top: 0;
}

.token-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin: 14px 0;
}

.token {
  min-width: 48px;
  border: 1px solid var(--line);
  border-radius: 5px;
  background: var(--paper);
  padding: 8px 10px;
  text-align: center;
}

.token.accepted {
  border-color: var(--target);
  background: var(--target-soft);
}

.token.rejected {
  border-color: var(--reject);
  background: var(--reject-soft);
  text-decoration: line-through;
}

.token.corrected {
  border-color: var(--focus);
  background: #eaf2f8;
}

.controls {
  display: grid;
  grid-template-columns: repeat(3, minmax(150px, 1fr));
  gap: 14px;
  margin: 14px 0;
}

.controls label {
  display: grid;
  gap: 5px;
  color: var(--muted);
  font-size: 0.88rem;
}

.controls input {
  width: 100%;
}

.metric-row {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin-top: 16px;
}

.metric {
  min-height: 92px;
  border: 1px solid var(--line);
  background: var(--paper);
  padding: 12px;
}

.metric output {
  display: block;
  color: var(--target);
  font-size: 1.5rem;
  font-weight: 700;
}

.bar-chart {
  display: grid;
  gap: 9px;
  margin: 16px 0;
}

.bar-row {
  display: grid;
  grid-template-columns: 90px 1fr 58px;
  gap: 10px;
  align-items: center;
}

.bar-track {
  height: 22px;
  background: #e4e8e5;
}

.bar {
  height: 100%;
  background: var(--target);
}

.bar.draft-bar {
  background: var(--draft);
}

.quiz-options {
  display: grid;
  gap: 8px;
  margin-top: 12px;
}

.quiz-options button {
  width: 100%;
  text-align: left;
}

.quiz-options button.correct {
  border-color: var(--target);
  background: var(--target-soft);
}

.quiz-options button.wrong {
  border-color: var(--reject);
  background: var(--reject-soft);
}

.feedback {
  min-height: 1.8em;
  margin-top: 10px;
  font-weight: 650;
}

.course-map {
  display: grid;
  gap: 0;
  margin: 28px 0;
  border-top: 1px solid var(--line);
}

.course-map a {
  display: grid;
  grid-template-columns: 80px 1fr;
  gap: 16px;
  border-bottom: 1px solid var(--line);
  padding: 18px 4px;
  color: var(--ink);
  text-decoration: none;
}

.course-map a:hover {
  background: var(--paper);
}

.course-map span:first-child {
  color: var(--draft);
  font-weight: 700;
}

.course-map strong {
  display: block;
}

.course-map small {
  color: var(--muted);
}

.source-list {
  font-size: 0.9rem;
}

.print-only {
  display: none;
}

@media (max-width: 760px) {
  body {
    font-size: 16px;
  }

  h1 {
    font-size: 2rem;
  }

  main {
    width: min(100% - 24px, 1040px);
    padding-top: 18px;
  }

  table {
    display: block;
    max-width: 100%;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  .pipeline,
  .two-col,
  .three-col,
  .controls,
  .metric-row {
    grid-template-columns: 1fr;
  }

  .pipeline > div {
    min-height: auto;
  }

  .bar-row {
    grid-template-columns: 72px 1fr 48px;
  }
}

@media print {
  body {
    background: white;
    color: black;
    font-size: 11pt;
  }

  main {
    width: 100%;
    padding: 0;
  }

  a {
    color: black;
  }

  .lesson-nav,
  .tool,
  .exercise {
    display: none;
  }

  .print-only {
    display: block;
  }

  .callout,
  .panel,
  table,
  pre {
    break-inside: avoid;
  }
}