:root {
  color-scheme: dark;
  --paper: #0b0e0c;
  --paper-raised: #12160f;
  --ink: #eef2ea;
  --muted: #9aa79a;
  --line: #232922;
  --accent: #63e68c;
  --accent-soft: rgba(99, 230, 140, 0.12);
  --accent-dark: #3fcf72;
  --code: #0a0d0a;
  --code-ink: #d8f5e1;
  --warn: #f0b429;
  --warn-soft: rgba(240, 180, 41, 0.12);
  --shadow: 0 16px 40px rgba(0, 0, 0, 0.4);
  --mono: "SFMono-Regular", ui-monospace, "JetBrains Mono", Consolas, "Liberation Mono", monospace;
  font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 10% 0%, rgba(99, 230, 140, 0.07), transparent 30rem),
    var(--paper);
  font-size: 17px;
  line-height: 1.72;
}

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
}

a:hover {
  color: var(--accent-dark);
}

.page {
  width: min(900px, calc(100% - 36px));
  margin: 0 auto;
  padding: 54px 0 88px;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  font-family: ui-serif, Georgia, Cambria, "Times New Roman", serif;
  font-weight: 650;
  line-height: 1.14;
  text-wrap: balance;
}

h1 {
  max-width: 780px;
  margin: 0;
  font-size: clamp(2.3rem, 7vw, 4.8rem);
  letter-spacing: -0.045em;
}

h2 {
  margin: 70px 0 16px;
  font-size: clamp(1.65rem, 4vw, 2.45rem);
  letter-spacing: -0.025em;
}

h3 {
  margin: 0 0 8px;
  font-size: 1.22rem;
}

.flush-heading {
  margin-top: 0;
}

.lede {
  max-width: 690px;
  margin: 22px 0 0;
  color: var(--muted);
  font-family: ui-serif, Georgia, Cambria, "Times New Roman", serif;
  font-size: clamp(1.18rem, 2.6vw, 1.48rem);
}

.meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 28px;
  color: var(--muted);
  font-size: 0.86rem;
}

.meta span {
  padding: 4px 10px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 253, 248, 0.68);
}

.card,
.quiz,
.template {
  margin: 22px 0;
  padding: clamp(20px, 5vw, 34px);
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--paper-raised);
  box-shadow: var(--shadow);
}

.idea {
  border-left: 4px solid var(--accent);
}

.warning {
  border-left: 4px solid var(--warn);
  background: var(--warn-soft);
}

.source-note {
  margin: 30px 0 8px;
  padding: 15px 4px 15px 18px;
  border-top: 1px solid color-mix(in srgb, var(--line) 72%, transparent);
  border-bottom: 1px solid color-mix(in srgb, var(--line) 72%, transparent);
  border-left: 3px solid var(--accent);
  background: transparent;
}

.source-note-warning {
  border-left-color: var(--warn);
}

.source-note p {
  margin: 0;
}

.source-note p + p {
  margin-top: 7px;
  color: var(--muted);
  font-size: 0.94rem;
}

.bridge {
  margin: 24px 0;
  color: var(--muted);
}

.learning-map {
  margin: 22px 0 30px;
  padding: 18px 22px;
  border-left: 3px solid var(--accent);
  background: color-mix(in srgb, var(--accent-soft) 42%, transparent);
}

.learning-map strong {
  display: block;
  margin-bottom: 8px;
}

.learning-map p {
  margin: 0;
}

.lesson-contract,
.object-map,
.misconception,
.worked-example,
.explain-checklist,
.lesson-connection {
  margin: 22px 0;
  padding: 20px 22px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: color-mix(in srgb, var(--paper-raised) 92%, var(--accent-soft));
}

.lesson-contract h3,
.object-map h3,
.misconception h3,
.worked-example h3,
.explain-checklist h3,
.lesson-connection h3 {
  margin-top: 0;
}

.explain-checklist h2 {
  margin-top: 0;
  font-size: clamp(1.45rem, 3vw, 2rem);
}

.object-map pre {
  margin-bottom: 10px;
}

.claim-tag {
  display: inline-block;
  margin-right: 0.42rem;
  padding: 0.12rem 0.5rem;
  border: 1px solid color-mix(in srgb, var(--accent) 58%, var(--line));
  border-radius: 999px;
  color: var(--accent-dark);
  background: var(--accent-soft);
  font-size: 0.76rem;
  font-weight: 800;
  letter-spacing: 0.02em;
  vertical-align: 0.08em;
}

.claim-tag.approx,
.claim-tag.hardware {
  border-color: color-mix(in srgb, var(--warn) 58%, var(--line));
  color: var(--warn);
  background: var(--warn-soft);
}

.misconception {
  border-left: 4px solid var(--warn);
}

.misconception p:last-child,
.lesson-connection p:last-child {
  margin-bottom: 0;
}

.explain-checklist ul {
  margin-bottom: 0;
  padding: 0;
  list-style: none;
}

.explain-checklist li {
  position: relative;
  margin: 10px 0;
  padding-left: 1.8rem;
}

.explain-checklist li::before {
  position: absolute;
  left: 0;
  color: var(--accent-dark);
  content: "□";
  font-weight: 900;
}

.concept-check {
  margin: 22px 0;
  padding: 18px 20px;
  border: 1px solid color-mix(in srgb, var(--accent) 42%, var(--line));
  border-radius: 14px;
  background: var(--paper-raised);
}

.concept-check > summary {
  color: var(--accent-dark);
  cursor: pointer;
  font-weight: 800;
}

.concept-check[open] > summary {
  margin-bottom: 14px;
}

.diagnosis {
  padding-left: 14px;
  border-left: 3px solid var(--warn);
  color: var(--warn);
}

.concept-figure {
  margin: 26px 0;
}

.concept-figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--paper-raised);
}

.concept-figure figcaption {
  margin-top: 9px;
}

.deep-dive {
  margin: 22px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.deep-dive > summary {
  padding: 14px 2px;
  color: var(--accent-dark);
  cursor: pointer;
  font-weight: 750;
}

.deep-dive[open] > summary {
  margin-bottom: 14px;
}

.deep-dive > :last-child {
  margin-bottom: 20px;
}

.takeaways {
  margin: 20px 0 0;
  padding-left: 1.5rem;
}

.takeaways li {
  margin: 10px 0;
}

.prose-outline {
  margin: 18px 0;
}

.prose-outline p {
  margin: 10px 0;
}

.loop {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin: 26px 0 12px;
  counter-reset: loop;
}

.loop article {
  position: relative;
  min-height: 160px;
  padding: 54px 18px 18px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--paper-raised);
}

.loop article::before {
  position: absolute;
  top: 16px;
  left: 18px;
  width: 27px;
  height: 27px;
  border-radius: 50%;
  color: #07130c;
  background: var(--accent);
  content: counter(loop);
  counter-increment: loop;
  font-size: 0.78rem;
  font-weight: 800;
  line-height: 27px;
  text-align: center;
}

.loop p {
  margin: 0;
  color: var(--muted);
  font-size: 0.91rem;
  line-height: 1.55;
}

code,
pre {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

code {
  padding: 0.12em 0.36em;
  border-radius: 5px;
  background: var(--paper-raised);
  border: 1px solid var(--line);
  font-size: 0.88em;
}

pre {
  overflow-x: auto;
  margin: 18px 0;
  padding: 22px;
  border-radius: 14px;
  color: var(--code-ink);
  background: var(--code);
  font-size: 0.87rem;
  line-height: 1.65;
  white-space: pre-wrap;
}

pre code {
  padding: 0;
  background: transparent;
  font-size: inherit;
}

.checklist {
  padding: 0;
  list-style: none;
}

.checklist li {
  position: relative;
  margin: 10px 0;
  padding-left: 30px;
}

.checklist li::before {
  position: absolute;
  left: 0;
  color: var(--accent);
  content: "✓";
  font-weight: 900;
}

.quiz-options {
  display: grid;
  gap: 10px;
  margin-top: 18px;
}

.quiz button {
  width: 100%;
  padding: 13px 16px;
  border: 1px solid var(--line);
  border-radius: 10px;
  color: var(--ink);
  background: var(--paper);
  cursor: pointer;
  font: inherit;
  text-align: left;
}

.quiz button:hover,
.quiz button:focus-visible {
  border-color: var(--accent);
  outline: 2px solid transparent;
  background: var(--accent-soft);
}

.quiz button[aria-pressed="true"] {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.quiz-feedback {
  min-height: 1.8em;
  margin: 16px 0 0;
  font-weight: 700;
}

.quiz-feedback[data-state="correct"] {
  color: var(--accent-dark);
}

.quiz-feedback[data-state="incorrect"] {
  color: #ff8a75;
}

.small,
figcaption,
footer {
  color: var(--muted);
  font-size: 0.86rem;
}

.rule {
  height: 1px;
  margin: 46px 0;
  border: 0;
  background: var(--line);
}

footer {
  margin-top: 74px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

table {
  width: 100%;
  border-collapse: collapse;
  background: var(--paper-raised);
}

th,
td {
  padding: 12px 14px;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

th {
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

@media (max-width: 720px) {
  .page {
    padding-top: 34px;
  }

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

@media (max-width: 460px) {
  .loop {
    grid-template-columns: 1fr;
  }
}

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

  .page {
    width: auto;
    padding: 0;
  }

  .card,
  .quiz,
  .template,
  .loop article {
    break-inside: avoid;
    box-shadow: none;
  }

  a {
    color: inherit;
  }
}

/* ===== CS336 textbook lesson layout ===== */
body.cs336-lesson .page {
  width: min(1100px, calc(100% - 40px));
  padding-top: 40px;
}

body.cs336-lesson > .pb-toc {
  display: none !important;
}

.lesson-hero {
  position: relative;
  padding: 26px 0 34px;
  border-bottom: 1px solid var(--line);
}

.lesson-hero h1 {
  max-width: 820px;
  font-size: clamp(2.4rem, 5.2vw, 3.9rem);
}

.lesson-hero .lede {
  max-width: 780px;
  margin-top: 16px;
  font-size: clamp(1.08rem, 2vw, 1.3rem);
}

.lesson-hero .lesson-secondary-summary {
  display: block;
}

.lesson-hero .meta {
  margin-top: 20px;
}

.lesson-hero .source-note {
  margin: 10px 0 0;
  padding-top: 12px;
  padding-bottom: 12px;
}

.lesson-source-details {
  width: fit-content;
  margin-top: 10px;
  color: var(--muted);
  font-size: 0.78rem;
}

.lesson-source-details > summary {
  cursor: pointer;
  font-weight: 650;
}

.lesson-opening {
  max-width: 820px;
  margin-top: 24px;
  padding: 20px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.lesson-opening .lesson-question,
.lesson-opening .learning-map,
.lesson-opening .lesson-contract {
  margin: 0;
  padding: 0;
  border: 0;
  border-radius: 0;
  background: transparent;
}

.lesson-opening .lesson-question {
  color: var(--ink);
  font-size: 1.02rem;
}

.lesson-opening .learning-map {
  margin-top: 14px;
  padding-left: 16px;
  border-left: 3px solid var(--accent);
}

.lesson-opening .learning-map strong,
.lesson-opening .lesson-prerequisite h3 {
  margin: 0 0 5px;
  color: var(--accent-dark);
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.lesson-opening .lesson-prerequisite {
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px solid color-mix(in srgb, var(--line) 72%, transparent);
  color: var(--muted);
  font-size: 0.92rem;
}

.lesson-opening .lesson-prerequisite p {
  margin: 0;
}

.lesson-pager {
  position: absolute;
  top: 26px;
  right: 0;
  display: flex;
  gap: 16px;
  font-size: 0.83rem;
}

.lesson-pager a {
  color: var(--muted);
  text-decoration: none;
}

.lesson-pager a:hover,
.lesson-pager a:focus-visible {
  color: var(--accent-dark);
  text-decoration: underline;
}

.lesson-shell {
  display: grid;
  grid-template-columns: minmax(0, 820px) minmax(200px, 230px);
  gap: 48px;
  align-items: start;
  margin-top: 20px;
}

.lesson-main {
  min-width: 0;
}

.lesson-main h2 {
  scroll-margin-top: 92px;
}

.lesson-main > .lesson-contract,
.lesson-main > .object-map {
  margin: 28px 0;
  padding: 20px 0;
  border-width: 1px 0;
  border-radius: 0;
  background: transparent;
}

.lesson-main > .object-map {
  margin-top: 12px;
}

.lesson-main .card,
.lesson-main .quiz,
.lesson-main .template,
.lesson-main .worked-example,
.lesson-main .misconception,
.lesson-main .explain-checklist,
.lesson-main .lesson-connection {
  box-shadow: none;
}

.lesson-main .lesson-connection {
  padding: 16px 0;
  border-width: 1px 0;
  border-radius: 0;
  background: transparent;
}

.lesson-main .lesson-connection h3 {
  margin-bottom: 5px;
  color: var(--accent-dark);
  font-size: 0.72rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.lesson-toc {
  position: sticky;
  top: 88px;
  max-height: calc(100vh - 112px);
  overflow-y: auto;
  padding: 18px 0 18px 18px;
  border-left: 1px solid var(--line);
}

.lesson-toc-label {
  display: flex;
  justify-content: space-between;
  margin: 0 0 12px;
  color: var(--muted);
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.11em;
  text-transform: uppercase;
}

.lesson-toc-progress {
  color: var(--accent);
  font-variant-numeric: tabular-nums;
}

.lesson-toc nav {
  display: grid;
  gap: 3px;
}

.lesson-toc a {
  padding: 6px 9px;
  border-left: 2px solid transparent;
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.35;
  text-decoration: none;
}

.lesson-toc a:hover,
.lesson-toc a:focus-visible,
.lesson-toc a.is-active {
  border-left-color: var(--accent);
  color: var(--ink);
  background: color-mix(in srgb, var(--accent-soft) 38%, transparent);
}

.lesson-toc-mobile {
  display: none;
}

.teaching-block {
  position: relative;
  margin: 28px 0;
  padding: 24px 22px 20px;
  border: 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  border-radius: 0;
  background: transparent;
}

.teaching-block:not(.concept-check-block)::before {
  display: block;
  margin-bottom: 10px;
  color: var(--accent-dark);
  content: attr(data-block-label);
  font-size: 0.72rem;
  font-weight: 850;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.teaching-block.mental-model {
  border-left: 3px solid var(--accent);
  background: color-mix(in srgb, var(--accent-soft) 24%, transparent);
}

.teaching-block.derivation-block {
  border-left: 3px solid var(--muted);
}

.teaching-block.misconception-block {
  border-left: 3px solid var(--warn);
  background: color-mix(in srgb, var(--warn-soft) 28%, transparent);
}

.teaching-block.concept-check-block {
  border-left: 3px solid var(--accent);
  background: color-mix(in srgb, var(--paper-raised) 82%, transparent);
}

.teaching-deep-dive {
  margin: 26px 0;
  padding: 14px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.teaching-deep-dive > summary::before {
  margin-right: 0.5rem;
  color: var(--muted);
  content: "Deep Dive";
  font-size: 0.68rem;
  font-weight: 850;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.deep-quiz-level {
  display: inline-block;
  min-width: 6.5rem;
  margin-right: 0.5rem;
  color: var(--accent-dark);
  font-size: 0.72rem;
  font-weight: 850;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.closed-book {
  padding: 26px 0;
  border-width: 1px 0;
  border-radius: 0;
  background: transparent;
}

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

.closed-book li {
  display: grid;
  grid-template-columns: 1.2rem 1fr;
  gap: 8px;
  margin: 0;
  padding: 10px 0;
  border-bottom: 1px solid color-mix(in srgb, var(--line) 72%, transparent);
}

.closed-book li > span:first-child {
  color: var(--accent);
  font-weight: 800;
}

.lesson-build-bridge {
  margin: 34px 0;
  padding: 22px 0 22px 20px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  border-left: 3px solid var(--accent);
}

.lesson-build-bridge h3 {
  margin: 6px 0 8px;
}

.lesson-build-kicker {
  color: var(--accent-dark);
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.lesson-build-bridge p {
  margin: 0 0 10px;
}

.lesson-build-bridge a {
  color: var(--accent-dark);
  font-weight: 750;
}

@media (max-width: 1040px) {
  body.cs336-lesson .page {
    width: min(820px, calc(100% - 36px));
  }

  .lesson-shell {
    grid-template-columns: minmax(0, 1fr);
    gap: 0;
  }

  .lesson-toc {
    display: none;
  }

  .lesson-toc-mobile {
    display: block;
    margin-top: 18px;
    padding: 12px 0;
    border-top: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
  }

  .lesson-toc-mobile summary {
    cursor: pointer;
    font-weight: 800;
  }

  .lesson-toc-mobile nav {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 6px 18px;
    margin-top: 12px;
  }

  .lesson-toc-mobile a {
    padding: 4px 0;
    color: var(--muted);
    font-size: 0.88rem;
    text-decoration: none;
  }

  .lesson-toc-mobile a.is-active {
    color: var(--accent-dark);
    font-weight: 750;
  }
}

@media (max-width: 720px) {
  body.cs336-lesson .page {
    width: min(100% - 28px, 820px);
    padding-top: 18px;
  }

  .lesson-hero {
    padding-top: 18px;
  }

  .lesson-pager {
    position: static;
    justify-content: space-between;
    margin-bottom: 18px;
  }

  .lesson-toc-mobile nav {
    grid-template-columns: 1fr;
  }

  .teaching-block {
    padding-right: 14px;
    padding-left: 16px;
  }
}

/* ===== Prism Syntax Highlighting ===== */
pre[class*="language-"] {
  background: var(--code) !important;
  margin: 18px 0;
  padding: 22px;
  border-radius: 14px;
  font-size: 0.85rem;
  line-height: 1.65;
  overflow-x: auto;
  border: 1px solid rgba(255,255,255,0.05);
}

code[class*="language-"] {
  font-family: "SF Mono", "Fira Code", Consolas, monospace;
  text-shadow: none;
}

.token.comment,
.token.prolog,
.token.doctype,
.token.cdata { color: #6b7a6d; }

.token.punctuation { color: #b9c4ba; }

.token.property,
.token.tag,
.token.boolean,
.token.number,
.token.constant,
.token.symbol { color: #63e68c; }

.token.selector,
.token.attr-name,
.token.string,
.token.char,
.token.builtin { color: #9ef0bb; }

.token.operator,
.token.entity,
.token.url { color: #7dd8c9; }

.token.atrule,
.token.attr-value,
.token.keyword { color: #ff8a75; }

.token.function,
.token.class-name { color: #7bc6ff; }

.token.regex,
.token.important,
.token.variable { color: #f0b429; }

.token.decorator,
.token.annotation { color: #7bc6ff; }

.token.string { color: #9ef0bb; }

.token.generic { color: #63e68c; }


/* Keep long equations usable on narrow screens. */
.katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 0.35rem 0;
}

/* ===== Deep practice: light structure for long-form technical reading ===== */
.before-start,
.concept-lab,
.deep-quiz,
.open-practice {
  margin: 42px 0;
}

.before-start {
  padding: 24px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.before-start h2,
.deep-quiz h2,
.open-practice h2 {
  margin-top: 0;
}

.before-start-grid,
.compare-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px 24px;
  margin-top: 18px;
}

.before-prompt,
.open-prompt {
  padding: 12px 0;
  border-bottom: 1px solid var(--line);
}

.before-prompt summary,
.open-prompt summary,
.deep-quiz-item summary {
  cursor: pointer;
  font-weight: 750;
}

.before-prompt p,
.open-guide p {
  margin-bottom: 0;
  color: var(--muted);
}

.claim-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin: 20px 0 0;
}

.claim-legend span {
  padding: 4px 8px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--paper-raised);
  font-size: 0.78rem;
}

.concept-lab {
  padding: 22px 0 22px 24px;
  border-left: 3px solid var(--accent);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.concept-lab-eyebrow,
.follow-up-label {
  margin: 0 0 12px;
  color: var(--accent-dark);
  font-size: 0.78rem;
  font-weight: 850;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.practice-question {
  margin: 0;
}

.practice-prompt {
  margin: 0 0 14px;
  font-weight: 700;
}

.practice-options {
  display: grid;
  gap: 8px;
  margin: 0;
  padding: 0;
  border: 0;
}

.practice-option {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  padding: 11px 13px;
  border: 1px solid var(--line);
  border-radius: 9px;
  background: var(--paper);
  cursor: pointer;
}

.practice-option:hover,
.practice-option:focus-within {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.practice-option input {
  margin-top: 0.28em;
  accent-color: var(--accent-dark);
}

.practice-option.is-correct {
  border-color: #3fcf72;
  background: rgba(99,230,140,.1);
}

.practice-option.is-selected-wrong {
  border-color: #ff8a75;
  background: rgba(255,107,94,.1);
}

.practice-actions {
  display: flex;
  gap: 10px;
  margin-top: 14px;
}

.practice-submit,
.practice-retry {
  padding: 9px 15px;
  border: 1px solid var(--accent-dark);
  border-radius: 8px;
  color: #07130c;
  background: var(--accent-dark);
  cursor: pointer;
  font: inherit;
  font-weight: 750;
}

.practice-retry {
  color: var(--accent-dark);
  background: transparent;
}

.practice-explanation:not(:empty) {
  margin-top: 16px;
  padding-top: 14px;
  border-top: 1px dashed var(--line);
}

.practice-result {
  font-weight: 850;
}

.practice-explanation.is-correct .practice-result {
  color: #9ef0bb;
}

.practice-explanation.is-incorrect .practice-result,
.practice-explanation.is-empty {
  color: #ffb3a8;
}

.option-reasons {
  margin-bottom: 0;
  padding-left: 1.4rem;
  color: var(--muted);
}

.option-reasons li {
  margin: 8px 0;
}

.option-reasons .is-answer {
  color: var(--ink);
}

.follow-up {
  margin-top: 20px;
  padding: 18px 0 0 18px;
  border-top: 1px solid var(--line);
  border-left: 2px solid var(--line);
}

.deep-quiz {
  padding-top: 8px;
  border-top: 2px solid var(--ink);
}

.deep-quiz-progress {
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.deep-quiz-stack {
  margin-top: 20px;
}

.deep-quiz-item {
  padding: 16px 0;
  border-bottom: 1px solid var(--line);
}

.deep-quiz-item > .practice-question {
  padding-top: 18px;
}

.open-practice {
  padding: 22px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.compare-grid > section {
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--paper-raised);
}

.compare-grid h3 {
  margin-top: 0;
}

@media (max-width: 720px) {
  .before-start-grid,
  .compare-grid {
    grid-template-columns: 1fr;
  }

  .concept-lab {
    padding-left: 16px;
  }

  .claim-legend {
    align-items: flex-start;
  }
}

@media print {
  .practice-actions {
    display: none;
  }

  .concept-lab,
  .deep-quiz-item,
  .before-prompt,
  .open-prompt {
    break-inside: avoid;
  }
}