.course-page {
  --course-tint: color-mix(in srgb, var(--accent) 9%, var(--surface));
  --course-tint-strong: color-mix(in srgb, var(--accent) 16%, var(--surface));
  --course-line-strong: color-mix(in srgb, var(--accent) 42%, var(--line));
  --course-muted-surface: color-mix(in srgb, var(--surface) 68%, var(--bg));
  width: min(920px, 100%);
  margin-inline: auto;
  overflow-wrap: anywhere;
}

.course-page [hidden] {
  display: none !important;
}

.course-page button,
.course-page input {
  font: inherit;
}

.course-page button {
  -webkit-tap-highlight-color: transparent;
}

.course-page :is(a, button, summary, input):focus-visible {
  outline: 2px solid var(--text);
  outline-offset: 3px;
}

.course-hero {
  position: relative;
  padding: clamp(42px, 8vw, 76px) 0 clamp(34px, 6vw, 58px);
  border-bottom: 1px solid var(--line);
}

.course-kicker {
  margin: 0 0 14px;
  color: var(--accent);
  font-size: 0.76rem;
  font-weight: 650;
  line-height: 1.4;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.course-title,
.course-hero h1 {
  max-width: 780px;
  margin: 0;
  font-family: var(--font-serif);
  font-size: clamp(2.55rem, 7.5vw, 5.25rem);
  font-weight: 600;
  line-height: 0.99;
  letter-spacing: -0.055em;
  text-wrap: balance;
}

.course-lead {
  max-width: 720px;
  margin: 24px 0 0;
  color: var(--muted);
  font-size: clamp(1rem, 2.1vw, 1.13rem);
  line-height: 1.88;
}

.course-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 0;
  margin: 28px 0 0;
  padding: 0;
  color: var(--text);
  font-size: 0.86rem;
  line-height: 1.4;
  list-style: none;
}

.course-stats > * {
  display: inline-flex;
  align-items: center;
  white-space: nowrap;
}

.course-stats > * + *::before {
  content: "";
  width: 1px;
  height: 0.9em;
  margin-inline: 13px;
  background: var(--line);
}

.course-stats dt {
  color: var(--accent);
  font-variant-numeric: tabular-nums;
  font-weight: 700;
}

.course-stats dd {
  margin: 0 0 0 4px;
  color: var(--muted);
}

.course-progress {
  margin: 28px 0 0;
  padding: 18px 20px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.course-progress-head,
.course-progress-copy {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 12px;
}

.course-progress-title,
.course-progress-copy > span {
  color: var(--text);
  font-size: 0.8rem;
  font-weight: 650;
  letter-spacing: 0.08em;
}

.course-progress > p {
  margin: 10px 0 0;
  color: var(--muted);
  font-size: 0.76rem;
  line-height: 1.55;
}

.course-progress [data-course-progress-label] {
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.5;
  text-align: right;
}

.course-progress-track {
  height: 7px;
  overflow: hidden;
  border-radius: var(--radius-pill);
  background: var(--course-muted-surface);
}

.course-progress [data-course-progress-fill] {
  display: block;
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: var(--accent);
  transition: width 320ms ease;
}

.course-guide,
.course-howto {
  margin: 22px 0 0;
  padding: 16px 18px;
  border-left: 3px solid var(--accent);
  background: var(--course-tint);
  color: var(--muted);
  font-size: 0.92rem;
  line-height: 1.78;
}

.course-guide strong,
.course-howto strong {
  color: var(--text);
  font-weight: 650;
}

.course-howto p {
  margin: 4px 0 0;
}

.course-index {
  margin: 48px 0;
  padding-bottom: 42px;
  border-bottom: 1px solid var(--line);
}

.course-index-title,
.course-index-heading h2 {
  margin: 0 0 16px;
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 650;
  line-height: 1.4;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.course-index-heading {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 16px;
}

.course-index-heading h2 {
  margin-bottom: 0;
}

.course-index-heading span {
  color: var(--muted);
  font-size: 0.76rem;
}

.course-index-list,
.course-index ol {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.course-index a {
  display: flex;
  min-height: 100%;
  align-items: baseline;
  gap: 8px;
  padding: 9px 10px;
  border: 1px solid transparent;
  border-radius: calc(var(--radius) - 2px);
  color: var(--muted);
  font-size: 0.78rem;
  line-height: 1.45;
}

.course-index a:hover {
  border-color: var(--line);
  background: var(--surface);
  color: var(--text);
}

.course-index-number,
.course-index li > a > span:first-child {
  flex: 0 0 auto;
  color: var(--accent);
  font-variant-numeric: tabular-nums;
  font-weight: 650;
}

.course-lessons {
  display: grid;
  gap: 14px;
}

.course-lesson {
  overflow: clip;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.course-lesson.is-current {
  border-color: var(--course-line-strong);
  box-shadow: inset 3px 0 0 var(--accent);
}

.course-lesson.is-complete {
  background: var(--course-muted-surface);
}

.course-lesson > summary {
  display: grid;
  grid-template-columns: 78px minmax(0, 1fr) auto 18px;
  align-items: center;
  gap: 14px;
  min-height: 76px;
  padding: 15px 20px;
  color: var(--text);
  cursor: pointer;
  list-style: none;
}

.course-lesson > summary::-webkit-details-marker {
  display: none;
}

.course-lesson > summary::after {
  content: "+";
  color: var(--accent);
  font-size: 1.15rem;
  font-weight: 400;
  line-height: 1;
  text-align: right;
}

.course-lesson[open] > summary::after {
  content: "−";
}

.course-lesson > summary:hover {
  background: var(--course-tint);
}

.course-lesson-number {
  color: var(--accent);
  font-size: 0.72rem;
  font-weight: 650;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  white-space: nowrap;
}

.course-lesson-title,
.course-lesson > summary h2 {
  font-family: var(--font-serif);
  font-size: clamp(1.08rem, 2.5vw, 1.34rem);
  font-weight: 600;
  line-height: 1.35;
  letter-spacing: -0.015em;
}

.course-lesson > summary h2 {
  margin: 0;
}

.course-lesson [data-lesson-status] {
  color: var(--muted);
  font-size: 0.76rem;
  line-height: 1.4;
  white-space: nowrap;
}

.course-lesson.is-complete [data-lesson-status] {
  color: var(--accent);
}

.course-lesson-body {
  padding: 26px 28px 30px;
  border-top: 1px solid var(--line);
}

.course-goal {
  margin: 0;
  padding: 15px 18px;
  border-left: 3px solid var(--accent);
  background: var(--course-tint);
  color: var(--text);
  font-size: 0.96rem;
  line-height: 1.78;
}

.course-goal strong {
  font-weight: 650;
}

.course-goal strong::after {
  content: " — ";
  color: var(--muted);
  font-weight: 400;
}

.course-plan {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 0.79rem;
  line-height: 1.65;
}

.course-section {
  margin-top: 30px;
}

.course-section-title,
.course-section > h3 {
  margin: 0 0 13px;
  color: var(--text);
  font-family: var(--font-serif);
  font-size: 1.12rem;
  font-weight: 600;
  line-height: 1.4;
  letter-spacing: -0.01em;
}

.course-laws,
.course-readings {
  margin: 0;
  padding: 0;
  list-style: none;
}

.course-law {
  padding: 14px 0;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.94rem;
  line-height: 1.82;
}

.course-law:last-child {
  border-bottom: 1px solid var(--line);
}

.course-law strong {
  color: var(--text);
  font-weight: 650;
}

.course-law h4 {
  margin: 0 0 4px;
  color: var(--text);
  font-size: 0.94rem;
  font-weight: 650;
  line-height: 1.55;
}

.course-law p {
  margin: 0;
}

.course-law code,
.course-question code,
.course-drill code {
  padding: 0.12em 0.34em;
  border: 1px solid var(--line);
  border-radius: calc(var(--radius) / 2);
  background: var(--course-muted-surface);
  color: var(--text);
  font-size: 0.88em;
}

.course-reading {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  gap: 14px;
  padding: 13px 0;
  border-top: 1px solid var(--line);
}

.course-reading:last-of-type {
  border-bottom: 1px solid var(--line);
}

.course-reading a {
  font-weight: 600;
  line-height: 1.55;
}

.course-reading-source,
.course-reading-original {
  color: var(--muted);
  font-size: 0.76rem;
  white-space: nowrap;
}

.course-reading-source a {
  margin-left: 5px;
  font-weight: 500;
}

.course-reading-prompt,
.course-reading-hint {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 0.86rem;
  line-height: 1.7;
}

.course-question {
  margin-top: 14px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--course-muted-surface);
}

.course-question:first-of-type {
  margin-top: 0;
}

.course-question-text,
.course-question-title {
  margin: 0 0 14px;
  color: var(--text);
  font-weight: 600;
  line-height: 1.7;
}

.course-question-number,
.course-question-title > span:first-child {
  display: inline-block;
  margin-right: 9px;
  color: var(--accent);
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.06em;
}

.course-question-options,
.course-options {
  display: grid;
  gap: 8px;
}

.course-question button[data-answer-index] {
  display: grid;
  grid-template-columns: 26px minmax(0, 1fr);
  align-items: start;
  gap: 10px;
  width: 100%;
  padding: 11px 13px;
  border: 1px solid var(--line);
  border-radius: calc(var(--radius) - 2px);
  background: var(--surface);
  color: var(--text);
  line-height: 1.62;
  text-align: left;
  cursor: pointer;
  transition: border-color 160ms ease, background-color 160ms ease;
}

.course-question button[data-answer-index]:hover:not([aria-disabled="true"]) {
  border-color: var(--course-line-strong);
  background: var(--course-tint);
}

.course-question button[data-answer-index][aria-disabled="true"] {
  cursor: default;
}

.course-answer-label,
.course-question button[data-answer-index] > span:first-child {
  display: inline-flex;
  width: 24px;
  height: 24px;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: 50%;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 700;
  line-height: 1;
}

.course-question button[data-answer-index].is-correct {
  border-color: var(--course-line-strong);
  background: var(--course-tint-strong);
}

.course-question button[data-answer-index].is-correct .course-answer-label,
.course-question button[data-answer-index].is-correct > span:first-child {
  border-color: var(--accent);
  background: var(--accent);
  color: var(--surface);
}

.course-question button[data-answer-index].is-wrong {
  border-color: var(--text);
  background: var(--surface);
}

.course-question button[data-answer-index].is-wrong .course-answer-label,
.course-question button[data-answer-index].is-wrong > span:first-child {
  border-color: var(--text);
  background: var(--text);
  color: var(--surface);
}

.course-verdict {
  margin: 15px 0 0;
  color: var(--text);
  font-size: 0.87rem;
  font-weight: 700;
}

.course-question.is-correct .course-verdict {
  color: var(--accent);
}

.course-explanation {
  margin: 8px 0 0;
  padding-top: 12px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.88rem;
  line-height: 1.78;
}

.course-explanation [data-verdict] {
  display: block;
  margin-bottom: 6px;
  color: var(--text);
}

.course-explanation p {
  margin: 0;
}

.course-question [data-redo] {
  margin-top: 12px;
  padding: 7px 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius-pill);
  background: var(--surface);
  color: var(--muted);
  font-size: 0.76rem;
  line-height: 1.2;
  cursor: pointer;
}

.course-question [data-redo]:hover {
  border-color: var(--course-line-strong);
  color: var(--accent);
}

.course-drill {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 13px;
  margin-top: 12px;
  padding: 16px 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--course-muted-surface);
  cursor: pointer;
}

.course-drill:first-of-type {
  margin-top: 0;
}

.course-drill.is-complete {
  border-color: var(--course-line-strong);
  background: var(--course-tint);
}

.course-drill input[type="checkbox"] {
  width: 17px;
  height: 17px;
  margin: 4px 0 0;
  accent-color: var(--accent);
}

.course-drill-level {
  display: inline-block;
  margin: 0 8px 5px 0;
  color: var(--accent);
  font-size: 0.69rem;
  font-weight: 700;
  line-height: 1.4;
  letter-spacing: 0.06em;
}

.course-drill-copy {
  display: block;
  min-width: 0;
}

.course-drill-copy > strong {
  color: var(--text);
  font-weight: 650;
}

.course-drill-copy > span:not(.course-drill-level),
.course-drill-copy > em {
  display: block;
  margin-top: 5px;
  color: var(--muted);
  font-size: 0.88rem;
  font-style: normal;
  line-height: 1.72;
}

.course-drill-copy > em {
  color: color-mix(in srgb, var(--text) 76%, var(--muted));
}

.course-drill-title {
  color: var(--text);
  font-weight: 650;
}

.course-drill-description,
.course-drill-acceptance {
  display: block;
  margin-top: 5px;
  color: var(--muted);
  font-size: 0.88rem;
  line-height: 1.72;
}

.course-drill-acceptance {
  color: color-mix(in srgb, var(--text) 76%, var(--muted));
}

.course-lesson-complete {
  display: flex;
  align-items: flex-start;
  gap: 11px;
  margin-top: 28px;
  padding: 15px 17px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--course-tint);
  color: var(--text);
  font-size: 0.9rem;
  font-weight: 600;
  line-height: 1.65;
  cursor: pointer;
}

.course-lesson-complete.is-complete {
  border-color: var(--course-line-strong);
  background: var(--course-tint-strong);
}

.course-lesson-complete input[type="checkbox"] {
  flex: 0 0 auto;
  width: 18px;
  height: 18px;
  margin: 3px 0 0;
  accent-color: var(--accent);
}

.course-footer,
.course-source-note {
  margin: 36px 0 0;
  color: var(--muted);
  font-size: 0.76rem;
  line-height: 1.7;
  text-align: center;
}

.course-source-note p {
  margin: 0 0 7px;
}

@media (max-width: 820px) {
  .course-index-list,
  .course-index ol {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .course-lesson > summary {
    grid-template-columns: 68px minmax(0, 1fr) 18px;
  }

  .course-lesson [data-lesson-status] {
    display: none;
  }
}

@media (max-width: 620px) {
  .course-hero {
    padding-top: 30px;
  }

  .course-title,
  .course-hero h1 {
    font-size: clamp(2.35rem, 13vw, 3.45rem);
  }

  .course-lead {
    margin-top: 18px;
    font-size: 0.98rem;
  }

  .course-progress {
    padding: 16px;
  }

  .course-progress-head,
  .course-progress-copy {
    display: block;
  }

  .course-progress [data-course-progress-label] {
    display: block;
    margin-top: 6px;
    text-align: left;
  }

  .course-index {
    margin: 36px 0;
    padding-bottom: 32px;
  }

  .course-index-list,
  .course-index ol {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .course-lesson > summary {
    grid-template-columns: minmax(0, 1fr) 18px;
    gap: 7px 12px;
    min-height: 72px;
    padding: 14px 16px;
  }

  .course-lesson-number {
    grid-column: 1;
    font-size: 0.68rem;
  }

  .course-lesson-title,
  .course-lesson > summary h2 {
    grid-column: 1;
    grid-row: 2;
  }

  .course-lesson > summary::after {
    grid-column: 2;
    grid-row: 1 / span 2;
  }

  .course-lesson-body {
    padding: 21px 16px 24px;
  }

  .course-reading {
    grid-template-columns: 1fr;
    gap: 4px;
  }

  .course-reading-source {
    white-space: normal;
  }

  .course-question {
    padding: 15px;
  }

  .course-question button[data-answer-index] {
    grid-template-columns: 24px minmax(0, 1fr);
    padding: 10px 11px;
  }

  .course-answer-label,
  .course-question button[data-answer-index] > span:first-child {
    width: 22px;
    height: 22px;
  }

  .course-drill {
    padding: 14px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .course-progress [data-course-progress-fill],
  .course-question button[data-answer-index] {
    transition: none;
  }
}