:root {
  color-scheme: dark;
  --bg: #1e1e2e;
  --panel: #181825;
  --deep: #11111b;
  --text: #cdd6f4;
  --muted: #a6adc8;
  --line: #38394e;
  --green: #a6e3a1;
  --blue: #89b4fa;
  --mauve: #cba6f7;
  --peach: #fab387;
  --mono: ui-monospace, SFMono-Regular, Consolas, monospace;
  --sidebar: 290px;
}
* {
  box-sizing: border-box;
}
html {
  scroll-behavior: smooth;
  scroll-padding-top: 100px;
}
body {
  margin: 0;
  background:
    radial-gradient(ellipse at 95% 0, #26332e55, transparent 42%), var(--bg);
  color: var(--text);
  font:
    16px/1.75 system-ui,
    sans-serif;
}
a {
  color: var(--blue);
  text-underline-offset: 4px;
}
button,
input,
textarea {
  font: inherit;
}
button,
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--text);
  border-radius: 8px;
  padding: 9px 14px;
  text-decoration: none;
  cursor: pointer;
  font: 12px/1.5 var(--mono);
}
button:hover,
.button:hover {
  border-color: var(--green);
}
button:disabled {
  opacity: 0.45;
  cursor: default;
}
.primary {
  background: #24382c;
  color: var(--green);
  border-color: #476449;
}
button:focus-visible,
a:focus-visible,
input:focus-visible,
textarea:focus-visible,
summary:focus-visible {
  outline: 3px solid var(--blue);
  outline-offset: 4px;
}
.skip {
  position: fixed;
  top: -80px;
  left: 10px;
  z-index: 20;
  background: var(--deep);
  padding: 10px;
}
.skip:focus {
  top: 10px;
}
header {
  height: 69px;
  position: fixed;
  inset: 0 0 auto;
  z-index: 5;
  background: #1e1e2ef5;
  border-bottom: 1px solid var(--line);
  padding: 0 25px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 15px;
}
.brand {
  font: 13px var(--mono);
  color: var(--text);
  text-decoration: none;
}
.brand span {
  color: var(--green);
}
.tools,
.row {
  display: flex;
  align-items: center;
  gap: 9px;
  flex-wrap: wrap;
}
.mobile-only {
  display: none;
}
.shell {
  display: grid;
  grid-template-columns: var(--sidebar) minmax(0, 1fr);
  padding-top: 69px;
  min-height: 100vh;
}
aside {
  position: fixed;
  top: 69px;
  left: 0;
  bottom: 0;
  width: var(--sidebar);
  overflow-y: auto;
  background: #181825aa;
  border-right: 1px solid var(--line);
  padding: 24px 17px;
}
.nav-intro {
  font: 11px var(--mono);
  letter-spacing: 0.12em;
  color: var(--muted);
  text-transform: uppercase;
  margin: 0 8px 14px;
}
.track-tabs {
  display: flex;
  gap: 7px;
  margin: 0 5px 18px;
}
.track-tabs a {
  font: 11px var(--mono);
  text-decoration: none;
  padding: 7px 10px;
  border: 1px solid var(--line);
  border-radius: 6px;
  color: var(--muted);
}
.track-tabs a.active {
  border-color: var(--green);
  color: var(--green);
  background: #24382c;
}
.search {
  width: 100%;
  background: var(--deep);
  color: var(--text);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 11px;
  font-size: 13px;
}
.search-wrap {
  padding: 0 5px;
  margin-bottom: 18px;
}
.lesson-nav {
  display: grid;
  gap: 5px;
}
.lesson-nav a {
  display: grid;
  grid-template-columns: 24px 1fr 16px;
  gap: 9px;
  align-items: start;
  padding: 11px 9px;
  border-radius: 8px;
  text-decoration: none;
  color: var(--muted);
  font-size: 12.5px;
  line-height: 1.5;
  border: 1px solid transparent;
}
.lesson-nav a:hover {
  background: #222233;
}
.lesson-nav a[aria-current="page"] {
  background: #26342d;
  border-color: #405744;
  color: var(--text);
}
.lesson-nav .num {
  font: 11px/1.8 var(--mono);
  color: var(--mauve);
}
.lesson-nav .done {
  color: var(--green);
}
.sidebar-foot {
  margin: 20px 7px;
  color: var(--muted);
  font: 11px/1.8 var(--mono);
}
.sidebar-foot a {
  display: block;
  margin-top: 10px;
}
main {
  grid-column: 2;
  min-width: 0;
  padding: 48px clamp(24px, 4vw, 70px) 90px;
  max-width: 1370px;
  width: 100%;
  margin: auto;
}
.eyebrow {
  font: 11px var(--mono);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--green);
  margin: 0 0 18px;
}
h1 {
  font-size: clamp(34px, 4.4vw, 62px);
  letter-spacing: -0.04em;
  line-height: 1.1;
  max-width: 920px;
  margin: 0 0 23px;
}
h1 span {
  color: var(--green);
}
.lead {
  font-size: 21px;
  line-height: 1.6;
  color: var(--muted);
  max-width: 780px;
  margin: 0 0 25px;
}
.meta {
  font: 12px var(--mono);
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  color: var(--muted);
  margin: 22px 0;
}
.badge {
  border: 1px solid var(--line);
  border-radius: 20px;
  padding: 5px 10px;
  font: 11px var(--mono);
  color: var(--mauve);
}
.hero {
  padding-bottom: 34px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 32px;
}
.progress-wrap {
  margin: 24px 0;
  max-width: 680px;
}
.progress-label {
  font: 12px var(--mono);
  color: var(--muted);
  display: flex;
  justify-content: space-between;
  margin-bottom: 9px;
}
.progress {
  height: 6px;
  border-radius: 5px;
  background: #313244;
  overflow: hidden;
}
.progress i {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--green), var(--blue));
  transition: width 0.2s;
}
.cards {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 15px;
  margin: 25px 0;
}
.course-card {
  border: 1px solid var(--line);
  background: var(--panel);
  border-radius: 13px;
  padding: 23px;
  display: flex;
  flex-direction: column;
  gap: 13px;
}
.course-card h2 {
  font-size: 20px;
  line-height: 1.3;
  margin: 0;
}
.course-card p {
  font-size: 14px;
  color: var(--muted);
  margin: 0;
}
.course-card .row {
  margin-top: auto;
  padding-top: 8px;
}
.course-card a {
  font: 12px var(--mono);
}
.step-tag {
  font: 11px var(--mono);
  color: var(--mauve);
}
.callout {
  background: #24342a66;
  border: 1px solid #405744;
  border-radius: 12px;
  padding: 22px 25px;
  margin: 25px 0;
  max-width: 850px;
}
.callout p {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 14px;
}
.callout strong {
  color: var(--green);
}
.lesson-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 170px;
  gap: 38px;
}
.lesson-body {
  min-width: 0;
  max-width: 810px;
}
.lesson-body section {
  margin: 0 0 43px;
  scroll-margin-top: 95px;
}
.lesson-body h2 {
  font-size: 25px;
  letter-spacing: -0.02em;
  line-height: 1.3;
  margin: 0 0 20px;
}
.lesson-body p {
  margin: 0 0 18px;
}
.lesson-body li {
  margin: 8px 0;
}
.lesson-body ul,
.lesson-body ol {
  padding-left: 23px;
}
.section-label {
  font: 10px var(--mono);
  color: var(--mauve);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 10px;
}
.toc {
  position: sticky;
  top: 99px;
  align-self: start;
  font: 11px/1.8 var(--mono);
}
.toc a {
  display: block;
  text-decoration: none;
  color: var(--muted);
  padding: 5px 0;
}
.toc a:hover {
  color: var(--green);
}
.objectives {
  margin: 25px 0;
  border-left: 3px solid var(--green);
  padding: 2px 0 2px 20px;
}
.objectives p {
  font: 11px var(--mono);
  color: var(--green);
  margin: 0 0 10px;
}
.objectives ul {
  margin: 0;
  padding-left: 18px;
  font-size: 14px;
  color: var(--muted);
}
.model {
  border: 1px solid var(--line);
  border-radius: 13px;
  background: var(--panel);
  padding: 21px;
  margin: 25px 0;
}
.model-head {
  font: 11px var(--mono);
  color: var(--mauve);
  margin-bottom: 15px;
}
.model-steps {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
}
.model-steps button {
  text-align: left;
  justify-content: start;
  font-size: 12px;
  padding: 13px;
}
.model-steps button[aria-pressed="true"] {
  color: var(--green);
  border-color: var(--green);
  background: #24382c;
}
.model-output {
  margin-top: 15px;
  padding: 17px;
  background: var(--deep);
  border-radius: 8px;
  font-size: 14px;
  min-height: 92px;
}
.codebox {
  border: 1px solid var(--line);
  border-radius: 11px;
  background: var(--deep);
  overflow: hidden;
  margin: 20px 0;
}
.codebar {
  padding: 9px 13px;
  background: var(--panel);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font: 11px var(--mono);
  color: var(--muted);
}
.codebar button {
  padding: 4px 10px;
}
pre {
  margin: 0;
  padding: 20px;
  overflow: auto;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  font: 12.5px/1.8 var(--mono);
  color: var(--green);
}
code {
  font-family: var(--mono);
}
details {
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #18182577;
  padding: 15px 19px;
  margin: 14px 0;
}
summary {
  font: 13px var(--mono);
  color: var(--blue);
  cursor: pointer;
}
details > div {
  margin-top: 17px;
  font-size: 14px;
}
.filelinks {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 20px 0;
}
.filelinks a {
  font: 11px var(--mono);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 7px 10px;
}
.question {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 22px;
  background: var(--panel);
}
fieldset {
  border: 0;
  padding: 0;
  margin: 0;
}
legend {
  font-weight: 600;
  line-height: 1.5;
  margin-bottom: 15px;
}
.answer {
  display: flex;
  gap: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px 15px;
  margin: 9px 0;
  cursor: pointer;
  font-size: 14px;
}
.answer input {
  accent-color: var(--green);
  flex-shrink: 0;
  width: 17px;
}
.feedback {
  margin-top: 17px;
  font-size: 14px;
  padding: 16px;
  border-left: 3px solid var(--peach);
  background: var(--deep);
}
.feedback.correct {
  border-color: var(--green);
}
.completion {
  background: #24342a66;
  border: 1px solid #405744;
  border-radius: 12px;
  padding: 22px;
  margin-top: 25px;
}
.completion label {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  font-size: 14px;
  margin: 18px 0;
}
.completion input {
  margin-top: 6px;
  accent-color: var(--green);
}
.status {
  font: 12px var(--mono);
  color: var(--muted);
  margin-top: 13px;
}
.status.success {
  color: var(--green);
}
textarea {
  width: 100%;
  min-height: 170px;
  background: var(--deep);
  color: var(--text);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 16px;
  resize: vertical;
  font-size: 14px;
  line-height: 1.7;
}
.notes-hint {
  font: 11px var(--mono);
  color: var(--muted);
  margin-top: 10px !important;
}
.references {
  font-size: 14px;
}
.references a {
  overflow-wrap: anywhere;
}
.lesson-nav-bottom {
  border-top: 1px solid var(--line);
  padding-top: 25px;
  display: flex;
  justify-content: space-between;
  gap: 15px;
  flex-wrap: wrap;
}
.notice {
  font: 12px/1.6 var(--mono);
  color: var(--peach);
  margin: 12px 0;
}
.empty {
  color: var(--muted);
  padding: 18px;
  font-size: 13px;
}
.sr {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
}
dialog {
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--line);
  border-radius: 12px;
  width: min(95vw, 450px);
  max-height: 90vh;
  padding: 20px;
}
dialog::backdrop {
  background: #11111bdd;
}
.dialog-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}
.source-note {
  color: var(--muted);
  font: 11px/1.8 var(--mono);
  margin-top: 35px;
}
.assessment {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
}
.assessment th,
.assessment td {
  text-align: left;
  border-bottom: 1px solid var(--line);
  padding: 10px 8px;
  vertical-align: top;
}
.focus-mode aside {
  display: none;
}
.focus-mode .shell {
  grid-template-columns: 1fr;
}
.focus-mode main {
  grid-column: 1;
  max-width: 1130px;
}
.focus-mode .mobile-only {
  display: inline-flex;
}
@media (min-width: 1600px) {
  main {
    padding-top: 65px;
  }
}
@media (max-width: 1200px) {
  .lesson-layout {
    grid-template-columns: minmax(0, 1fr);
  }
  .toc {
    display: none;
  }
  :root {
    --sidebar: 250px;
  }
  main {
    padding-left: 30px;
    padding-right: 30px;
  }
}
@media (max-width: 860px) {
  aside {
    display: none;
  }
  .shell {
    grid-template-columns: 1fr;
  }
  main {
    grid-column: 1;
    padding: 35px 22px 70px;
  }
  .mobile-only {
    display: inline-flex;
  }
  .desktop-only {
    display: none;
  }
  header {
    padding: 0 17px;
  }
  .brand {
    font-size: 12px;
  }
  .tools {
    gap: 6px;
  }
  .tools button {
    padding: 7px 9px;
  }
  .cards {
    gap: 12px;
  }
  .lead {
    font-size: 19px;
  }
}
@media (max-width: 520px) {
  .cards {
    grid-template-columns: 1fr;
  }
  .brand .brand-extra {
    display: none;
  }
  .course-card {
    padding: 21px;
  }
  h1 {
    font-size: 37px;
  }
  .model-steps {
    grid-template-columns: 1fr;
  }
  .callout {
    padding: 18px;
  }
  .lesson-body h2 {
    font-size: 23px;
  }
  .question,
  .completion {
    padding: 18px;
  }
  .assessment {
    font-size: 11px;
  }
  .tools .export-label {
    display: none;
  }
}
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  * {
    transition: none !important;
  }
}
@media print {
  header,
  aside,
  .toc,
  .tools,
  .model-steps,
  .codebar button,
  .lesson-nav-bottom,
  .completion button,
  .skip,
  .filelinks {
    display: none !important;
  }
  .shell {
    display: block;
    padding: 0;
  }
  main {
    padding: 0;
    max-width: none;
  }
  .lesson-layout {
    display: block;
  }
  .lesson-body {
    max-width: none;
  }
  body {
    background: white;
    color: #111;
    font-size: 11pt;
  }
  .lead,
  .meta,
  .source-note,
  .notes-hint {
    color: #333;
  }
  h1 {
    font-size: 28pt;
  }
  .callout,
  .model,
  .question,
  .completion,
  details,
  .codebox {
    background: white;
    border: 1px solid #bbb;
    break-inside: avoid;
  }
  pre,
  .model-output,
  textarea,
  .feedback {
    background: #f5f5f5;
    color: #111;
  }
  a {
    color: #17426d;
  }
  .hero {
    padding-bottom: 15px;
  }
  .lesson-body section {
    margin-bottom: 22px;
  }
  details {
    display: block;
  }
  details > div {
    display: block;
  }
  textarea {
    min-height: 100px;
  }
  header {
    position: static;
  }
}
[hidden] {
  display: none !important;
}
/* Long identifiers and technical terms remain readable on narrow screens. */
h1,
.lesson-body p,
.lesson-body li,
legend,
.source-note {
  overflow-wrap: anywhere;
}