:root {
  color-scheme: light;
  --blue: #1d4ed8;
  --teal: #0f766e;
  --ink: #0f172a;
  --muted: #475569;
  --line: #e2e8f0;
  font-family:
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    "Malgun Gothic",
    sans-serif;
  color: var(--ink);
  background: #fff;
  line-height: 1.7;
  font-synthesis: none;
}
* {
  box-sizing: border-box;
}
html {
  scroll-padding-top: 6rem;
}
body {
  margin: 0;
  word-break: keep-all;
  overflow-wrap: anywhere;
}
a {
  color: var(--blue);
  text-underline-offset: 4px;
}
a:hover {
  text-decoration: underline;
}
button,
input {
  font: inherit;
}
button,
a,
input,
summary {
  touch-action: manipulation;
}
button,
summary {
  cursor: pointer;
}
button:disabled {
  cursor: not-allowed;
}
button:focus-visible,
a:focus-visible,
input:focus-visible,
summary:focus-visible {
  outline: 3px solid #60a5fa;
  outline-offset: 4px;
}
h1,
h2,
h3,
h4,
p {
  margin: 0;
}
h1 {
  font-size: clamp(2rem, 5vw, 3.4rem);
  line-height: 1.25;
  letter-spacing: -0.04em;
}
h2 {
  font-size: clamp(1.4rem, 3vw, 1.9rem);
  line-height: 1.5;
  letter-spacing: -0.03em;
}
h3 {
  font-size: 1.15rem;
  line-height: 1.8;
}
h4 {
  font-size: 1rem;
  line-height: 1.8;
}
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}
.skip {
  position: fixed;
  top: -100px;
  left: 1rem;
  padding: 0.7rem 1rem;
  background: var(--ink);
  color: white;
  z-index: 100;
}
.skip:focus {
  top: 0.8rem;
}
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem max(1.25rem, calc((100vw - 1180px) / 2));
  background: #ffffffed;
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
  font-size: 0.875rem;
}
.site-header a {
  text-decoration: none;
  font-weight: 650;
}
.brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  color: var(--ink);
}
.brand-mark {
  display: grid;
  place-items: center;
  width: 2.2rem;
  height: 2.2rem;
  border-radius: 0.65rem;
  background: var(--blue);
  color: #fff;
  font-weight: 800;
}
.brand-detail {
  color: #64748b;
  font-weight: 450;
  padding-left: 0.25rem;
}
.hero {
  max-width: 1180px;
  margin: auto;
  padding: 4rem 1.5rem 3.5rem;
  border-bottom: 1px solid var(--line);
}
.eyebrow {
  color: var(--teal);
  font-size: 0.82rem;
  font-weight: 750;
  margin-bottom: 0.65rem;
}
.intro {
  margin-top: 1.25rem;
  max-width: 45rem;
  color: var(--muted);
  font-size: 1.1rem;
  line-height: 1.9;
}
.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1.3rem;
}
.tags span {
  font-size: 0.76rem;
  font-weight: 600;
  border: 1px solid #bfdbfe;
  border-radius: 999px;
  padding: 0.3rem 0.75rem;
  background: #eff6ff;
  color: #1e40af;
}
.hero-actions,
.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  margin-top: 1.5rem;
}
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  min-height: 46px;
  border-radius: 0.75rem;
  border: 1px solid transparent;
  padding: 0.65rem 1rem;
  font-size: 0.9rem;
  font-weight: 650;
  text-decoration: none;
  transition: background 0.15s;
}
.button:hover {
  text-decoration: none;
}
.primary {
  background: var(--blue);
  color: #fff;
}
.primary:hover {
  background: #1e40af;
}
.primary:disabled {
  background: #e2e8f0;
  color: #64748b;
}
.secondary {
  background: #fff;
  border-color: #cbd5e1;
  color: var(--muted);
}
.secondary:hover {
  background: #f8fafc;
}
.full {
  width: 100%;
  margin-top: 1.3rem;
}
.text-button {
  border: 0;
  background: transparent;
  color: var(--blue);
  text-decoration: underline;
  text-underline-offset: 4px;
  min-height: 44px;
  padding: 0.4rem 0.2rem;
  font-size: 0.85rem;
}
.study-layout {
  max-width: 1180px;
  display: grid;
  grid-template-columns: 230px minmax(0, 1fr);
  gap: 4.5rem;
  margin: 0 auto;
  padding: 3rem 1.5rem 5rem;
}
.study-layout aside {
  align-self: start;
  position: sticky;
  top: 6rem;
}
.toc {
  border: 1px solid var(--line);
  border-radius: 1rem;
  padding: 1.2rem;
  background: #f8fafc;
}
.toc h2 {
  font-size: 0.8rem;
  color: #64748b;
  letter-spacing: 0;
}
.toc ol {
  list-style: none;
  padding: 0;
  margin: 0.8rem 0;
}
.toc li {
  margin: 0.7rem 0;
}
.toc a {
  display: block;
  min-height: 36px;
  padding: 0.35rem 0;
  color: #334155;
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 600;
}
.toc a:hover {
  color: var(--blue);
}
.toc .toc-practice {
  font-size: 0.78rem;
  font-weight: 450;
  color: var(--teal);
}
.toc .toc-resource {
  border-top: 1px solid var(--line);
  margin-top: 1rem;
  padding-top: 0.9rem;
  font-size: 0.8rem;
}
.small {
  font-size: 0.78rem;
  color: #64748b;
  line-height: 1.9;
}
.audience {
  padding: 1rem 0.3rem;
}
.document {
  min-width: 0;
  max-width: 760px;
}
.chapter {
  scroll-margin-top: 7rem;
}
.reading {
  font-size: 1.06rem;
  line-height: 2.12;
  color: #334155;
  margin-top: 1.5rem;
}
.recall {
  margin-top: 2rem;
  padding: 1.5rem;
  border: 1px solid #99f6e4;
  border-radius: 1rem;
  background: #f0fdfa;
  scroll-margin-top: 7rem;
}
.recall h3 {
  color: #134e4a;
}
.recall summary {
  font-weight: 600;
  color: var(--teal);
  padding: 0.8rem 0;
  min-height: 44px;
}
.recall ul {
  padding-left: 1.25rem;
  margin: 0.5rem 0 1rem;
}
.recall li {
  margin: 0.6rem 0;
  color: #134e4a;
}
.recall .small {
  color: #3f6661;
}
.practice {
  border-top: 1px solid var(--line);
  padding-top: 2.5rem;
  margin-top: 3rem;
  scroll-margin-top: 7rem;
}
.practice > p:not(.eyebrow) {
  color: var(--muted);
  font-size: 0.9rem;
  margin-top: 0.8rem;
}
.quiz-shell {
  margin-top: 1.25rem;
}
.notice {
  padding: 1rem;
  border: 1px solid #bfdbfe;
  border-radius: 0.8rem;
  background: #eff6ff;
  color: #1e3a8a;
  font-size: 0.88rem;
  margin-bottom: 1rem;
}
.notice p + p {
  margin-top: 0.7rem;
}
.warning {
  border-color: #fde68a;
  background: #fffbeb;
  color: #78350f;
}
.save-choice {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
  background: #f8fafc;
  border: 1px solid var(--line);
  border-radius: 0.8rem;
  padding: 1rem;
  font-size: 0.85rem;
  font-weight: 600;
}
.save-choice input {
  width: 1rem;
  height: 1rem;
  accent-color: var(--blue);
  margin-top: 0.3rem;
  flex-shrink: 0;
}
.save-choice small {
  display: block;
  font-weight: 400;
  font-size: 0.76rem;
  color: #64748b;
  line-height: 1.8;
  margin-top: 0.3rem;
}
.question-card {
  border: 1px solid var(--line);
  border-radius: 1.2rem;
  padding: 1.7rem;
  margin-top: 1rem;
  box-shadow: 0 2px 5px #0f172a04;
}
.question-card > p {
  font-size: 0.9rem;
  color: var(--muted);
  margin-top: 0.7rem;
}
.question-card h3 {
  scroll-margin-top: 7rem;
  outline: none;
  border-radius: 0.2rem;
}
.question-card h3:focus-visible,
.feedback-title:focus-visible {
  outline: 3px solid #93c5fd;
  outline-offset: 5px;
}
.question-meta {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  color: var(--blue);
  font-size: 0.8rem;
  font-weight: 650;
}
.question-meta span + span {
  color: #64748b;
  font-weight: 450;
}
progress {
  display: block;
  width: 100%;
  height: 5px;
  margin: 1rem 0 1.5rem;
  accent-color: var(--blue);
}
fieldset {
  border: 0;
  padding: 0;
  margin: 1.4rem 0 0;
  min-width: 0;
}
.choice {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  min-height: 58px;
  padding: 0.8rem 1rem;
  border: 1px solid var(--line);
  border-radius: 0.8rem;
  margin-top: 0.65rem;
  font-size: 0.9rem;
  cursor: pointer;
}
.choice.selected {
  background: #eff6ff;
  border-color: var(--blue);
  color: #1e3a8a;
}
.choice:focus-within {
  outline: 2px solid #93c5fd;
  outline-offset: 2px;
}
.choice input {
  width: 1rem;
  height: 1rem;
  accent-color: var(--blue);
  flex-shrink: 0;
}
.option-number {
  color: #64748b;
  font-size: 0.75rem;
}
.answer-label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  margin-top: 1.4rem;
}
.answer-label input {
  display: block;
  width: 100%;
  min-height: 54px;
  border: 1px solid #cbd5e1;
  border-radius: 0.8rem;
  padding: 0.7rem 1rem;
  margin: 0.5rem 0;
  font-size: 1rem;
  color: var(--ink);
  background: #fff;
}
.answer-label input:disabled {
  background: #f8fafc;
}
.feedback {
  padding: 1.3rem;
  margin-top: 1.5rem;
  border: 1px solid #99f6e4;
  border-radius: 0.8rem;
  background: #f0fdfa;
  font-size: 0.88rem;
  line-height: 1.9;
}
.feedback.again {
  border-color: #fde68a;
  background: #fffbeb;
}
.feedback p + p {
  margin-top: 0.75rem;
}
.feedback-title {
  font-size: 1rem;
  font-weight: 750;
  scroll-margin-top: 7rem;
  outline: none;
}
.feedback .remember {
  font-weight: 600;
}
.feedback a {
  display: inline-block;
  margin-top: 1rem;
  min-height: 36px;
}
.result {
  background: linear-gradient(135deg, #f0fdfa, #fff);
}
.result-list {
  list-style: none;
  padding: 0;
  margin: 1.5rem 0;
}
.result-list li {
  border: 1px solid var(--line);
  border-radius: 0.8rem;
  padding: 1.1rem;
  background: white;
  margin-top: 1rem;
}
.result-list p {
  font-size: 0.85rem;
  line-height: 1.9;
  margin-top: 0.6rem;
  color: var(--muted);
}
.result-list .eyebrow {
  font-size: 0.72rem;
  color: var(--teal);
}
.resources {
  margin-top: 3rem;
  padding: 1.7rem;
  border: 1px solid var(--line);
  border-radius: 1rem;
  background: #f8fafc;
  scroll-margin-top: 7rem;
}
.resources > p:not(.eyebrow) {
  font-size: 0.88rem;
  color: var(--muted);
  margin-top: 1rem;
  line-height: 1.95;
}
.back-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 2rem;
  font-size: 0.85rem;
}
.back-links a {
  min-height: 44px;
  padding: 0.6rem 0;
}
footer {
  border-top: 1px solid var(--line);
  padding: 1.5rem;
  text-align: center;
  font-size: 0.8rem;
  color: #64748b;
}
.print-only {
  display: none;
}
@media (max-width: 800px) {
  .study-layout {
    grid-template-columns: 1fr;
    gap: 2rem;
    padding-top: 2rem;
  }
  .study-layout aside {
    position: static;
  }
  .toc ol {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.5rem;
  }
  .audience {
    display: none;
  }
  .hero {
    padding-top: 2.5rem;
    padding-bottom: 2.5rem;
  }
  .brand-detail {
    display: none;
  }
  .site-header {
    font-size: 0.76rem;
  }
  .site-header > a:last-child {
    max-width: 11rem;
    text-align: right;
  }
  .question-card,
  .recall,
  .resources {
    padding: 1.2rem;
  }
  .reading {
    font-size: 1rem;
  }
  .button-row .button {
    flex: 1;
    min-width: 130px;
  }
  .hero-actions {
    align-items: stretch;
  }
  .hero-actions .button {
    flex: 1;
    min-width: 140px;
  }
}
@media (prefers-reduced-motion: reduce) {
  * {
    transition: none !important;
    scroll-behavior: auto !important;
  }
}
@media print {
  @page {
    size: A4;
    margin: 18mm;
  }
  html,
  body {
    font-size: 11pt;
    color: #111;
    background: white;
  }
  .site-header,
  .hero-actions,
  .toc,
  .audience,
  .quiz-shell,
  .practice > p,
  .practice > h2,
  .back-links,
  footer,
  .skip,
  .resources .hero-actions {
    display: none !important;
  }
  .hero {
    padding: 0 0 7mm;
    border: 0;
  }
  .study-layout {
    display: block;
    max-width: none;
    padding: 0;
  }
  .document {
    max-width: none;
  }
  .chapter {
    break-inside: auto;
  }
  .reading {
    font-size: 11pt;
    line-height: 1.8;
  }
  .recall {
    background: white;
    border: 1px solid #777;
    padding: 5mm;
  }
  .recall details > * {
    display: block !important;
  }
  .recall summary {
    display: none;
  }
  .recall details {
    content-visibility: visible;
  }
  .recall li {
    color: #111;
  }
  .resources {
    margin-top: 7mm;
    padding: 5mm;
    background: white;
  }
  .print-only {
    display: block;
    break-before: page;
  }
  .print-question {
    break-inside: avoid;
    margin: 7mm 0;
  }
  .print-question h3 {
    font-size: 11pt;
  }
  .print-question li {
    margin: 3mm 0;
  }
  .answer-line {
    margin: 7mm 0;
  }
  a {
    color: #111;
    text-decoration: none;
  }
  .tags span {
    background: white;
    border-color: #777;
    color: #111;
  }
  .eyebrow,
  .small,
  .recall .small {
    color: #444 !important;
  }
}