.learning-hero {
  padding: 48px 0 38px;
}
.learning-hero h1 {
  max-width: 23ch;
  font-size: clamp(38px, 5vw, 66px);
}
.learning-hero .lede {
  max-width: 58ch;
  margin: 20px 0 26px;
}
.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  padding-top: 28px;
  font-size: 13px;
  color: var(--muted);
}
.breadcrumbs a {
  color: var(--muted);
}
.learning-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 230px;
  gap: 70px;
  align-items: start;
  padding: 40px 0 80px;
}
.guide {
  min-width: 0;
  max-width: 790px;
}
.guide .guide-meta {
  font-size: 13px;
  color: var(--muted);
  margin-bottom: 30px;
}
.guide section {
  margin-bottom: 54px;
}
.guide h2 {
  font-size: clamp(26px, 3vw, 34px);
  line-height: 1.2;
  margin: 0 0 20px;
}
.guide h3 {
  font-size: 21px;
  line-height: 1.35;
  margin: 26px 0 12px;
}
.guide p,
.guide li {
  line-height: 1.85;
  margin-bottom: 18px;
}
.guide ul,
.guide ol {
  padding-left: 24px;
}
.guide .worked {
  margin: 28px 0;
  padding: 28px;
}
.guide .worked p:last-child,
.guide .worked li:last-child {
  margin-bottom: 0;
}
.contents {
  position: sticky;
  top: 32px;
  font-size: 13px;
  border-left: 1px solid var(--line);
  padding-left: 24px;
}
.contents strong {
  display: block;
  margin-bottom: 14px;
}
.contents a {
  display: block;
  padding: 7px 0;
  text-decoration: none;
  color: var(--muted);
}
.contents a:hover {
  color: var(--blue);
  text-decoration: underline;
}
.contents .contents-extra {
  border-top: 1px solid var(--line);
  padding-top: 18px;
  margin-top: 18px;
}
.tool-intro {
  margin-bottom: 22px;
  max-width: 72ch;
  color: var(--muted);
}
.standalone-fold {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(270px, 0.75fr);
  gap: 44px;
  align-items: center;
  padding: 30px 40px;
  background: var(--panel);
  border-radius: 24px;
  border: 1px solid var(--line);
}
.standalone-fold .fold-demo {
  min-width: 0;
}
.standalone-fold h2 {
  font-size: 27px;
  margin-bottom: 20px;
}
.standalone-fold p {
  margin-bottom: 18px;
}
.standalone-fold .fold-readout {
  margin: 16px 0 20px;
}
.standalone-fold .fold-readout span {
  font-size: 13px;
}
.diagram {
  margin: 24px 0 30px;
}
.diagram img,
.question-diagram {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
}
.diagram figcaption {
  font-size: 13px;
  line-height: 1.65;
  color: var(--muted);
  margin-top: 12px;
}
.net-gallery {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  margin: 28px 0;
}
.net-gallery figure {
  min-width: 0;
}
.net-gallery svg {
  display: block;
  width: 100%;
  height: auto;
  background: #fff;
  border-radius: 12px;
  border: 1px solid var(--line);
}
.net-gallery figcaption {
  margin-top: 6px;
  font-size: 12px;
  color: var(--muted);
}
.practice-intro {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 24px;
}
.practice-intro h2 {
  margin: 0;
}
.practice-intro [data-progress] {
  font-size: 13px;
  color: var(--muted);
}
.practice-form {
  margin-bottom: 54px;
}
.practice-question {
  min-width: 0;
  margin: 0 0 24px;
  padding: 22px 26px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--surface);
}
.practice-question legend {
  padding: 0 8px;
  font-weight: 700;
  font-size: 16px;
  max-width: 100%;
}
.practice-question > p {
  color: var(--muted);
  margin-bottom: 18px;
  font-size: 14px;
}
.question-diagram {
  display: block;
  max-width: 400px;
  height: auto;
  margin: 0 auto 18px;
}
.answer-options {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}
.answer-option {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px;
  min-height: 48px;
  border: 1px solid var(--line);
  border-radius: 8px;
  cursor: pointer;
  font-size: 14px;
}
.answer-option:has(input:checked) {
  border-color: var(--blue);
  background: var(--blue-soft);
}
.answer-option:has(input:focus-visible) {
  outline: 3px solid var(--blue);
  outline-offset: 3px;
}
.answer-option input {
  flex: none;
  width: 18px;
  height: 18px;
  margin: 0;
  accent-color: var(--blue);
}
.practice-question details {
  margin-top: 18px;
  font-size: 14px;
}
.practice-question summary {
  color: var(--blue);
  cursor: pointer;
  min-height: 44px;
  display: list-item;
  padding-top: 12px;
}
.practice-question details p {
  margin: 12px 0;
  line-height: 1.8;
}
[data-feedback]:empty {
  display: none;
}
.practice-question [data-feedback] {
  color: var(--ink);
  margin: 18px 0 0;
  font-weight: 700;
}
.practice-question[data-state="incorrect"] {
  border-style: dashed;
  border-width: 2px;
}
.practice-question[data-state="correct"] {
  border-color: var(--blue);
}
.practice-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}
.practice-result {
  margin: 26px 0;
  padding: 24px;
  border-left: 4px solid var(--blue);
  background: var(--blue-soft);
  font-weight: 600;
  line-height: 1.8;
}
.practice-result:focus {
  outline: 3px solid var(--blue);
  outline-offset: 5px;
}
.notice {
  border-left: 3px solid var(--blue);
  padding: 8px 0 8px 22px;
  margin-bottom: 36px;
  color: var(--muted);
}
.notice p:last-child {
  margin-bottom: 0;
}
.guide table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
  margin: 24px 0;
}
.guide td,
.guide th {
  padding: 12px;
  text-align: left;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}
.guide th {
  color: var(--muted);
  font-size: 12px;
}
.related-guides {
  padding: 30px 0;
  border-top: 1px solid var(--line);
}
.related-guides h2 {
  margin-bottom: 16px;
}
.related-guides a {
  display: inline-block;
  margin: 0 22px 14px 0;
  min-height: 44px;
  padding-top: 10px;
}
.guide-app {
  display: grid;
  grid-template-columns: 1fr 130px;
  gap: 28px;
  align-items: center;
  background: var(--panel);
  padding: 28px;
  border-radius: 16px;
  margin-bottom: 40px;
}
.guide-app h2 {
  font-size: 26px;
  margin-bottom: 16px;
}
.guide-app p {
  font-size: 14px;
  line-height: 1.75;
}
.guide-app img {
  border-radius: 14px;
}
.web-practice {
  margin: 100px 0;
}
.web-practice h2 {
  margin-bottom: 18px;
}
.web-practice > p {
  max-width: 65ch;
  color: var(--muted);
  margin-bottom: 30px;
}
.web-practice-links {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 0 36px;
}
.web-practice-links a {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 20px;
  padding: 25px 0;
  border-bottom: 1px solid var(--line);
  text-decoration: none;
  color: var(--ink);
}
.web-practice-links a:first-child {
  grid-row: span 2;
  border-bottom: 0;
  background: var(--blue-soft);
  border-radius: 16px;
  padding: 30px;
}
.web-practice-links strong {
  display: block;
  font-size: 22px;
  letter-spacing: -0.03em;
}
.web-practice-links small {
  display: block;
  font-size: 13px;
  color: var(--muted);
  margin-top: 10px;
  line-height: 1.65;
}
.web-practice-links a > span:last-child {
  color: var(--blue);
}
.web-practice-links a:hover strong {
  color: var(--blue);
}
@media (max-width: 1050px) {
  .learning-layout {
    gap: 40px;
    grid-template-columns: minmax(0, 1fr) 180px;
  }
}
@media (max-width: 800px) {
  .learning-layout {
    display: flex;
    flex-direction: column-reverse;
    gap: 36px;
  }
  .contents {
    position: static;
    width: 100%;
    border-left: 0;
    border-bottom: 1px solid var(--line);
    padding: 0 0 22px;
  }
  .contents a {
    display: inline-block;
    padding: 8px 18px 8px 0;
  }
  .contents .contents-extra {
    display: none;
  }
  .standalone-fold {
    grid-template-columns: 1fr;
    gap: 30px;
    padding: 24px;
  }
  .standalone-fold .fold-demo {
    max-width: 420px;
    width: 100%;
    margin-inline: auto;
  }
  .web-practice {
    margin: 70px 0;
  }
  .web-practice-links {
    grid-template-columns: 1fr;
  }
  .web-practice-links a:first-child {
    grid-row: auto;
  }
}
@media (max-width: 560px) {
  .learning-hero {
    padding: 36px 0 30px;
  }
  .learning-hero h1 {
    font-size: 38px;
  }
  .learning-hero .lede {
    font-size: 17px;
  }
  .learning-layout {
    padding-top: 30px;
  }
  .guide section {
    margin-bottom: 38px;
  }
  .guide .worked {
    padding: 20px;
  }
  .net-gallery {
    grid-template-columns: 1fr 1fr;
    gap: 12px;
  }
  .practice-question {
    padding: 18px 14px;
  }
  .answer-options {
    grid-template-columns: 1fr;
  }
  .practice-question legend {
    font-size: 15px;
  }
  .guide-app {
    grid-template-columns: 1fr;
    padding: 22px;
  }
  .guide-app img {
    display: none;
  }
  .standalone-fold {
    padding: 18px 12px;
  }
  .standalone-fold .fold-demo {
    --unit: 56px;
  }
  .guide td,
  .guide th {
    padding: 10px 6px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .learning-hero .btn,
  .practice-actions .btn {
    transition: none;
  }
}