:root,
html[data-theme="dark"] {
  color-scheme: dark;
  --paper: #090d16;
  --card: #111a27;
  --ink: #eef0e9;
  --muted: #a0adbe;
  --line: #29384b;
  --green: #78dce0;
  --soft: #172736;
  --gold: #e7c27b;
  --rust: #ff8b77;
  --serif: "Barlow Condensed", "Arial Narrow", sans-serif;
  --shadow: 0 15px 35px #0005;
}
body {
  font-family: "DM Sans", sans-serif;
  background: var(--paper);
  font-size: 14px;
}
h1,
h2,
h3 {
  color: var(--ink);
}
h1,
h2,
.chapter-card h3 {
  font-family: var(--serif);
  font-weight: 600;
  letter-spacing: 0.2px;
}
h1 {
  font-weight: 700;
}
.sidebar {
  background: #0d1420;
  padding-top: 28px;
}
.brand {
  font-size: 18px;
  letter-spacing: 0.2px;
}
.brandmark {
  background: var(--accent);
  color: #090d16;
  border-radius: 2px;
  font-size: 25px;
  line-height: 1;
  padding: 7px 10px;
}
.brand small {
  font: 8px var(--mono);
  letter-spacing: 1px;
  color: var(--muted);
}
.navlabel {
  font: 8px var(--mono);
  color: #8797ab;
  letter-spacing: 1.4px;
}
.nav a {
  font-size: 12px;
  border-radius: 2px;
  color: #b2becd;
  padding: 12px 11px;
}
.nav a.active {
  background: #1a2938;
  color: var(--cyan);
  box-shadow: inset 2px 0 var(--cyan);
}
.nav a:hover {
  background: #172331;
  color: var(--ink);
}
.nav a > span {
  color: var(--accent);
  width: 16px;
}
.topbar {
  height: 73px;
  padding: 0 36px;
  background: #0d1420;
  gap: 16px;
}
.search-launch {
  width: 260px;
  font-size: 11px;
  background: #151f2d;
  border-radius: 3px;
  color: #a0adbe;
}
.search-launch:hover {
  border-color: var(--cyan);
}
.breadcrumb {
  font-size: 11px;
}
.top-right {
  gap: 12px;
}
.pill {
  background: #172e35;
  color: #a7e2de;
  border-radius: 2px;
  font: 8px var(--mono);
  letter-spacing: 0.3px;
}
.eyebrow,
.chapter-tag,
.chapter-num {
  font-family: var(--mono);
  font-size: 9px;
  letter-spacing: 1px;
  color: var(--muted);
}
.main {
  padding: 30px 36px 44px;
}
.hero {
  background: linear-gradient(115deg, #1c2636, #111b2a);
  border-radius: 3px;
  border-color: #344157;
  min-height: 314px;
}
.hero-copy {
  padding: 31px;
}
.hero h1 {
  font: 700 clamp(36px, 3.4vw, 55px)/1.02 var(--serif);
  letter-spacing: 0.2px;
  margin: 18px 0;
}
.hero p {
  color: #b3c0cf;
  font-size: 12px;
}
.hero .eyebrow {
  color: #ff8b77;
  font-size: 9px;
}
.hero-art {
  background: radial-gradient(#78dce018 1px, transparent 1px);
  background-size: 13px 13px;
  border-left: 1px solid #344157;
  padding: 20px;
  min-height: 250px;
}
.hero-art svg {
  max-height: 260px;
  filter: drop-shadow(0 0 18px #78dce012);
}
.hero-art svg path {
  stroke: #5ba4b3;
}
.hero-art svg g[fill] {
  fill: #162c3a;
}
.hero-art svg circle {
  stroke: #78dce0;
}
.hero-art svg text {
  fill: #a5e3e2;
}
.button {
  border-radius: 2px;
  font-size: 11px;
  min-height: 40px;
  background: #172331;
  color: var(--ink);
  padding: 9px 13px;
  border: 1px solid #3b4c60;
  transition:
    background 0.2s,
    transform 0.2s;
}
.button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #090d16;
  font-weight: 700;
}
.button:hover {
  filter: none;
  background: #253b4a;
  transform: translateY(-1px);
}
.button.primary:hover {
  background: #ff8973;
}
.button-row {
  gap: 9px;
}
.hero .button-row .button {
  font-size: 10px;
}
.section-head h2 {
  font: 600 22px var(--serif);
  letter-spacing: 0.3px;
}
.text-link {
  color: var(--cyan);
  font-size: 11px;
}
.chapter-card {
  border-radius: 3px;
  position: relative;
  min-height: 220px;
  padding: 21px;
  background: linear-gradient(150deg, #152030, #101925);
}
.chapter-card:hover {
  border-color: #6697a7;
  box-shadow: 0 10px 30px #0005;
}
.chapter-card h3 {
  font-size: 25px;
  line-height: 1.1;
  min-height: 55px;
}
.chapter-card p {
  font-size: 11px;
  line-height: 1.8;
  min-height: 40px;
}
.chapter-top {
  margin-bottom: 19px;
}
.chapter-icon,
.chapter-icon.c2,
.chapter-icon.c3 {
  border-radius: 2px;
  background: #19313b;
  border: 1px solid #345261;
  color: #92e0e2;
  font-family: var(--mono);
  font-size: 24px;
}
.chapter-icon.c2 {
  color: #e7c27b;
  background: #302b24;
  border-color: #534936;
}
.chapter-icon.c3 {
  color: #c4a5e9;
  background: #29243a;
  border-color: #49415f;
}
.chapter-num {
  font-size: 8px;
  color: #a0adbe;
}
.card-footer {
  font-size: 10px;
  border-color: var(--line);
}
.progressbar {
  background: #243043;
  border-radius: 0;
  height: 3px;
}
.progressbar span,
.progressbar div {
  background: var(--cyan);
}
.panel,
.method-card,
.formula-card,
.course-list,
.quiz-card {
  border-radius: 3px;
  background: var(--card);
}
.panel h2 {
  font: 600 22px var(--serif);
}
.panel p,
.panel li {
  line-height: 1.8;
}
.method-row {
  border-color: var(--line);
}
.method-row .num {
  color: var(--accent);
}
.method-row strong {
  font-size: 12px;
}
.method-row small {
  font-size: 11px;
}
.mini-note,
.tool-note,
.metric,
.formula-chip,
.callout,
.callout.green,
.example,
.lesson-figure {
  background: #152634;
  color: #bfcedc;
  border-color: #2c4354;
  border-radius: 3px;
}
.callout strong {
  color: var(--cyan);
}
.formula-chip {
  color: #a5e5df;
}
.progress-ring {
  border-color: #3c666b;
  color: var(--cyan);
  font-family: var(--mono);
  font-size: 17px;
}
.side-bottom {
  padding: 14px 5px 0;
}
.source-badge {
  border-color: var(--line);
  padding-top: 16px;
}
.source-badge strong {
  font-size: 10px;
}
.source-badge .dot {
  background: var(--cyan);
}
.source-badge p {
  font-size: 10px;
}
.source-badge a {
  font-size: 9px;
}
.page-intro h1 {
  font-size: 42px;
}
.page-intro .eyebrow {
  color: var(--accent-ink);
}
.page-intro p {
  font-size: 13px;
}
.reading .topic-title {
  font-size: 38px;
}
.reading {
  padding: 28px;
}
.article {
  font-size: 14px;
  line-height: 1.9;
}
.article h2,
.article h3 {
  font-family: var(--serif);
  color: var(--ink);
}
.article strong {
  color: #a6e3df;
}
.article code,
.article th {
  background: #1b2b3d;
  color: #c9e8ea;
}
.article blockquote {
  border-color: #4a7385;
  color: #bdccdc;
}
.article td,
.article th {
  border-color: var(--line);
}
.lesson-figure {
  padding: 18px;
}
.lesson-figure text {
  fill: var(--ink) !important;
}
.lesson-figure svg [fill="#fff"],
.lesson-figure svg [fill="#ffffff"],
.lesson-figure svg [fill="#f8f8f8"],
.lesson-figure svg [fill="#f5f7f1"] {
  fill: #1e3040;
}
.lesson-figure svg [stroke] {
  stroke: #6babbc;
}
.lesson-figure svg [fill="#31574c"] {
  fill: #78dce0;
}
.lesson-figure svg marker path {
  fill: #78dce0;
}
.topic-link {
  border-color: var(--line);
  color: #bdc8d4;
}
.topic-link:hover,
.topic-link.active {
  background: #1a2c3e;
  color: var(--cyan);
}
.course-list h3 {
  background: #182432;
  color: var(--ink);
}
.topic-link.active {
  border-color: var(--cyan);
}
.filter {
  background: #162332;
  color: #c0ccdb;
  border-radius: 2px;
}
.filter.active {
  background: #78dce0;
  color: #0b1520;
}
.method-card h3 {
  font: 600 25px var(--serif);
}
.formula-big,
.formula-card .formula {
  color: var(--cyan);
}
.exam-banner {
  background: #172e3d;
  color: var(--ink);
  border: 1px solid #395569;
  border-radius: 3px;
}
.exam-banner p {
  color: #b8c9d7;
}
.lab-svg,
.graph-drawing {
  background: #121f30;
  border-color: #30485e;
}
.lab-svg text,
.graph-drawing text {
  fill: #d1e3ec;
}
.lab-svg [stroke] {
  stroke: #78dce0;
}
.lab-svg [fill="#aa6246"] {
  fill: #e7c27b;
}
.lab-svg [fill="#203a35"] {
  fill: #78dce0;
}
.graph-drawing circle {
  fill: #1a3243;
  stroke: #78dce0;
}
.graph-drawing line {
  stroke: #6f9eae;
}
.graph-drawing .hl {
  stroke: #ff8b77;
}
.metric strong {
  color: var(--cyan);
}
.matrix button,
.matrix td.bit {
  background: #1a2c3e;
  border-color: #3a5167;
  color: var(--ink);
}
.matrix button.on {
  background: #78dce0;
  color: #090d16;
}
.matrix td.added {
  background: #3c3027;
  color: #e7c27b;
  border-color: #987643;
}
.status-item.yes,
.choice.correct,
.feedback,
.answer-feedback {
  background: #15332e;
  color: #b9efdc;
}
.status-item.no,
.choice.wrong,
.feedback.wrong,
.answer-feedback.incorrect {
  background: #38232d;
  color: #f0bbc6;
}
.choice {
  border-color: #384d63;
  color: var(--ink);
  background: #172331;
  border-radius: 3px;
}
.choice:hover,
.choice.selected {
  background: #234052;
}
.choice.correct {
  border-color: #81d4ac;
}
.choice.wrong {
  border-color: #ef9bac;
}
.error {
  color: #ffa088;
}
.question-layout textarea,
input,
textarea,
select,
.field,
.search-box,
.search-box input {
  background: #0e1826;
  color: var(--ink);
  border-color: #3b5067;
  border-radius: 3px;
}
input::placeholder,
textarea::placeholder {
  color: #91a2b6;
}
.search-result:hover {
  background: #1a2d3e;
}
.skip-link {
  background: var(--accent);
  color: #090d16;
}
.footer {
  color: var(--muted);
  font-size: 10px;
}
.footer a {
  color: var(--cyan);
}
#toast,
#toast.shown {
  background: #78dce0;
  color: #090d16;
}
#toast.shown {
  opacity: 1;
}
.focus-console {
  border: 1px solid #34485a;
  background: #121f2d;
  padding: 12px;
  margin-bottom: 18px;
}
.focus-console label {
  font: 8px var(--mono);
  letter-spacing: 1px;
  color: var(--accent-ink);
}
.focus-clock {
  font: 500 28px var(--mono);
  color: var(--cyan);
  margin: 6px 0;
}
.focus-controls {
  display: flex;
  gap: 8px;
}
.focus-controls button {
  font: 9px var(--mono);
  padding: 5px 8px;
  border: 1px solid #3c5265;
  border-radius: 2px;
  background: #1b2c3d;
}
.focus-controls button:first-child {
  color: var(--cyan);
}
.focus-status {
  font: 8px/1.5 var(--mono);
  color: var(--muted);
  margin: 8px 0 0;
}
@media (max-width: 1100px) {
  .hero h1 {
    font-size: 39px;
  }
  .topbar {
    padding: 0 26px;
  }
  .breadcrumb {
    display: none;
  }
  .top-right {
    margin-left: auto;
  }
  .main {
    padding: 26px;
  }
  .hero-copy {
    padding: 26px;
  }
  .hero .button-row .button {
    font-size: 9px;
  }
  .hero-art {
    padding: 12px;
  }
}
@media (max-width: 800px) {
  .topbar {
    height: 62px;
    padding: 0 18px;
  }
  .top-right {
    margin-left: 0;
    flex: 1;
  }
  .search-launch {
    width: auto;
    flex: 1;
    max-width: none;
    justify-content: start;
    font-size: 10px;
  }
  .search-launch span {
    font-size: 12px;
  }
  .search-launch kbd {
    display: none;
  }
  .top-right .pill {
    display: none;
  }
  .menu-btn {
    font-size: 20px;
    color: var(--cyan);
  }
  .main {
    padding: 20px 18px 36px;
  }
  .hero-copy {
    padding: 27px 23px;
  }
  .hero h1 {
    font-size: 43px;
  }
  .hero p {
    font-size: 12px;
  }
  .hero-art {
    border-left: 0;
    border-top: 1px solid var(--line);
    min-height: 180px;
    max-height: 200px;
    padding: 0 30px;
  }
  .hero-art svg {
    height: 210px;
    max-height: 220px;
  }
  .chapter-card {
    padding: 20px;
  }
  .page-intro h1 {
    font-size: 36px;
  }
  .reading {
    padding: 20px;
  }
  .reading .topic-title {
    font-size: 34px;
  }
  .article {
    font-size: 13px;
  }
  .section-head h2 {
    font-size: 20px;
  }
  .section-head .text-link {
    font-size: 10px;
  }
  .focus-console {
    margin: 10px 0 15px;
  }
  .source-badge {
    padding-top: 12px;
  }
  .sidebar {
    overflow-y: auto;
  }
  .source-badge p {
    margin: 5px 0;
  }
  .brand {
    padding-bottom: 20px;
  }
  .nav a {
    padding: 10px 12px;
  }
  .topbar .search-launch {
    font-size: 10px;
  }
  .mobile-dim.shown {
    z-index: 14;
  }
  .sidebar.open {
    z-index: 30;
  }
  .section-head {
    gap: 10px;
  }
  .hero .button-row .button {
    font-size: 10px;
  }
}
@media (max-width: 360px) {
  .hero h1 {
    font-size: 36px;
  }
  .hero .button-row .button {
    font-size: 9px;
  }
  .hero-copy {
    padding: 24px 18px;
  }
  .reading {
    padding: 16px;
  }
  .main {
    padding: 18px 12px;
  }
  .section-head {
    align-items: start;
  }
  .section-head .text-link {
    font-size: 8px;
    max-width: 80px;
  }
}

/* Original generated lesson diagrams: dark cel fills with readable labels. */
.lesson-figure svg [fill="#e8eee3"],
.lesson-figure svg [fill="#fffef8"] {
  fill: #172c3d;
}
.lesson-figure svg [stroke="#ccd4c3"] {
  stroke: #486278;
}