/* Shared reading surfaces. Chapter colour identifies subject, never correctness. */
:root {
  color-scheme: light;
  --background: #f3f6f6;
  --surface: #ffffff;
  --subtle: #eaf1f0;
  --ink: #182d35;
  --muted: #4d626a;
  --border: #c8d6d7;
  --accent: #086b60;
  --on-accent: #ffffff;
  --accent-soft: #e0f2ed;
  --focus: #2158c0;
  --warn: #725108;
  --warn-bg: #fff5d9;
  --chapter-1: #086b60;
  --chapter-2: #4c51a6;
  --chapter-3: #a43a56;
  --chapter-4: #896000;
  --shadow: 0 12px 32px rgb(18 45 52 / 6%);
  --radius: 12px;
  font-family:
    "Avenir Next", Avenir, "Segoe UI", "PingFang SC", "Microsoft YaHei",
    sans-serif;
  font-size: 16px;
  line-height: 1.65;
  accent-color: var(--accent);
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --background: #101b23;
  --surface: #172630;
  --subtle: #20353e;
  --ink: #e8f0f1;
  --muted: #b4c7ce;
  --border: #47606a;
  --accent: #8ce1cf;
  --on-accent: #102c27;
  --accent-soft: #1f403c;
  --focus: #93baff;
  --warn: #f7d382;
  --warn-bg: #3b331e;
  --chapter-1: #8ce1cf;
  --chapter-2: #b6baff;
  --chapter-3: #ffb6c8;
  --chapter-4: #f7d382;
  --shadow: 0 12px 32px rgb(0 0 0 / 12%);
}
* {
  box-sizing: border-box;
}
[hidden] {
  display: none !important;
}
html {
  scroll-padding-top: 100px;
  scrollbar-color: var(--border) var(--background);
}
body {
  margin: 0;
  background: var(--background);
  color: var(--ink);
}
::selection {
  background: var(--accent);
  color: var(--on-accent);
}
a {
  color: var(--accent);
  text-underline-offset: 4px;
}
a:hover {
  text-decoration-thickness: 2px;
}
button,
input,
textarea {
  font: inherit;
}
button,
a {
  -webkit-tap-highlight-color: transparent;
}
button {
  cursor: pointer;
}
button:disabled {
  opacity: 0.45;
  cursor: default;
}
:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 4px;
}
h1,
h2,
h3,
p {
  margin: 0 0 1rem;
}
h1,
h2,
h3 {
  line-height: 1.25;
  text-wrap: balance;
}
h1 {
  font-size: 2.75rem;
  letter-spacing: -0.035em;
}
h2 {
  font-size: 1.65rem;
  letter-spacing: -0.02em;
}
h3 {
  font-size: 1.2rem;
}
ul,
ol {
  padding-inline-start: 1.5rem;
}
li + li {
  margin-top: 0.65rem;
}
main,
body > footer {
  width: min(1180px, 100%);
  margin-inline: auto;
  padding-inline: 32px;
}
.zh {
  display: block;
  color: var(--muted);
  font-size: 0.9em;
  line-height: 1.65;
  margin-top: 0.25rem;
  font-weight: 400;
}
.zh:empty {
  display: none;
}
:root.hide-zh .zh {
  display: none !important;
}
h1 > .zh {
  font-size: 1.2rem;
  letter-spacing: 0;
  margin-top: 0.8rem;
}
h2 > .zh,
h3 > .zh {
  font-size: 1rem;
  margin-top: 0.4rem;
  letter-spacing: 0;
}
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}
.skip {
  position: fixed;
  left: 20px;
  top: -100px;
  z-index: 100;
  background: var(--surface);
  padding: 12px;
}
.skip:focus {
  top: 10px;
}
.site-header {
  display: flex;
  align-items: center;
  gap: 32px;
  padding: 16px max(32px, calc((100vw - 1116px) / 2));
  border-bottom: 1px solid var(--border);
  background: var(--surface);
}
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--ink);
  text-decoration: none;
  font-size: 1.35rem;
  font-weight: 750;
  line-height: 1.25;
  flex-shrink: 0;
}
.brand-mark {
  width: 42px;
  height: 46px;
  display: grid;
  place-content: center;
  border: 1.5px solid var(--accent);
  border-radius: 8px;
  color: var(--accent);
  position: relative;
  font-size: 1.5rem;
}
.brand-mark > span {
  position: absolute;
  right: -5px;
  bottom: -5px;
  font-size: 14px;
  background: var(--surface);
}
.brand-sub {
  display: block;
  font-size: 0.73rem;
  font-weight: 500;
  margin-top: 3px;
  color: var(--muted);
}
.site-header nav {
  display: flex;
  gap: 22px;
  margin-left: auto;
  align-items: center;
}
.site-header nav a {
  padding-block: 10px;
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 650;
  text-decoration: none;
}
.site-header nav a[aria-current] {
  color: var(--accent);
  text-decoration: underline;
  text-decoration-thickness: 2px;
}
.preferences {
  display: flex;
  gap: 8px;
}
.compact {
  min-width: 44px;
  min-height: 44px;
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 6px 10px;
}
.compact[aria-pressed="true"] {
  background: var(--accent-soft);
  color: var(--accent);
  border-color: var(--accent);
}
.home-intro {
  display: grid;
  grid-template-columns: 1.3fr 1fr;
  gap: 60px;
  align-items: center;
  padding-block: 64px 60px;
}
.home-intro h1 > .ms {
  white-space: pre-line;
}
.lead {
  font-size: 1.1rem;
  max-width: 60ch;
}
.small {
  font-size: 0.85rem;
  color: var(--muted);
}
.measure {
  max-width: 75ch;
}
.actions {
  display: flex;
  gap: 12px;
  align-items: center;
  flex-wrap: wrap;
}
.primary,
.secondary,
.text-link,
.bookmark {
  display: inline-flex;
  gap: 8px;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  font-size: 0.95rem;
  padding: 10px 16px;
  border: 1px solid transparent;
  border-radius: 8px;
  text-decoration: none;
  line-height: 1.45;
}
.primary {
  background: var(--accent);
  color: var(--on-accent);
  font-weight: 650;
}
.primary .zh {
  color: inherit;
}
.secondary {
  color: var(--ink);
  background: var(--surface);
  border-color: var(--border);
}
.text-link {
  color: var(--accent);
  background: transparent;
  padding-inline: 0;
  text-decoration: underline;
}
.bookmark {
  background: var(--surface);
  color: var(--muted);
  border-color: var(--border);
  font-size: 0.85rem;
}
.bookmark.is-saved {
  border-color: var(--accent);
  background: var(--accent-soft);
  color: var(--accent);
}
.bookmark.is-saved .zh {
  color: inherit;
}
button:hover:not(:disabled),
.primary:hover,
.secondary:hover {
  filter: brightness(0.96);
}
.actions .zh,
button .zh,
.primary > .zh,
.secondary > .zh,
.text-link > .zh {
  display: inline;
  font-size: 0.85em;
  margin: 0;
}
.paper-note {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 30px;
  box-shadow: var(--shadow);
}
.paper-note h2 {
  font-size: 1.35rem;
}
.paper-note p:last-child {
  margin-bottom: 0;
}
.checklist {
  list-style: decimal;
  padding-left: 22px;
}
.section {
  padding-block: 32px;
}
.section-heading {
  display: flex;
  gap: 24px;
  align-items: center;
  justify-content: space-between;
}
.chapter-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 26px 36px;
}
.chapter {
  min-width: 0;
}
.chapter-1 {
  --chapter: var(--chapter-1);
}
.chapter-2 {
  --chapter: var(--chapter-2);
}
.chapter-3 {
  --chapter: var(--chapter-3);
}
.chapter-4 {
  --chapter: var(--chapter-4);
}
.chapter-head {
  display: flex;
  gap: 16px;
  align-items: center;
  padding-block: 20px;
  border-bottom: 2px solid var(--chapter);
}
.chapter-head h3,
.chapter-head p {
  margin: 0;
}
.chapter-number {
  font-size: 2.4rem;
  line-height: 1;
  font-weight: 650;
  color: var(--chapter);
}
.topic-row {
  display: grid;
  grid-template-columns: 28px minmax(0, 1fr) auto;
  gap: 10px;
  align-items: start;
  border-bottom: 1px solid var(--border);
  padding-block: 18px;
  color: var(--ink);
  text-decoration: none;
}
.topic-row:hover {
  background: var(--subtle);
}
.row-number {
  font-variant-numeric: tabular-nums;
  color: var(--chapter);
  font-size: 0.85rem;
  padding-top: 3px;
}
.topic-row strong {
  font-weight: 650;
  font-size: 1rem;
}
.topic-row strong .zh {
  font-size: 0.86rem;
}
.topic-desc {
  display: block;
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.8rem;
}
.topic-code {
  display: block;
  font-size: 0.78rem;
  font-weight: 650;
  color: var(--accent);
  margin-bottom: 6px;
  overflow-wrap: anywhere;
}
.topic-desc .zh {
  font-size: 1em;
}
.row-end {
  color: var(--muted);
  font-size: 0.75rem;
  white-space: nowrap;
  padding-top: 4px;
}
.row-end > span {
  margin-left: 6px;
  font-size: 1rem;
}
.mock-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-top: 28px;
}
.mock-card {
  display: flex;
  gap: 24px;
  padding: 28px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--ink);
  text-decoration: none;
}
.mock-card .small {
  margin-bottom: 18px;
}
.mock-letter {
  font-size: 3rem;
  font-weight: 650;
  line-height: 1;
  color: var(--accent);
}
.review-banner {
  padding: 32px;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  margin-top: 36px;
}
.review-banner p {
  max-width: 72ch;
}
body > footer {
  margin-top: 64px;
  padding-block: 26px 36px;
  border-top: 1px solid var(--border);
}
body > footer p {
  margin-bottom: 8px;
  font-size: 0.85rem;
}
.page-intro {
  padding-block: 32px;
}
.page-intro h1 {
  font-size: 2.2rem;
  margin-block: 20px 18px;
}
.page-intro > p {
  max-width: 80ch;
}
.back {
  display: inline-flex;
  gap: 12px;
  min-height: 44px;
  align-items: center;
  font-size: 0.85rem;
}
.back .zh {
  display: inline;
  margin: 0;
}
.eyebrow {
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 600;
}
.notice {
  padding: 16px 20px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--subtle);
  font-size: 0.95rem;
}
.workbook {
  display: grid;
  grid-template-columns: 218px minmax(0, 1fr);
  gap: 38px;
  align-items: start;
}
.workbook-content, .question-rail {
  min-width: 0;
}
.question-picker > summary {
  display: none;
}
.question-rail {
  position: sticky;
  top: 24px;
  font-size: 0.9rem;
}
.question-picker > button {
  width: 100%;
  margin-top: 8px;
}
.question-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 4px;
  margin-bottom: 20px;
}
.question-grid a {
  display: grid;
  place-content: center;
  min-height: 44px;
  border: 1px solid transparent;
  border-radius: 6px;
  color: var(--muted);
  text-decoration: none;
  font-variant-numeric: tabular-nums;
}
.question-grid a[aria-current] {
  color: var(--on-accent);
  background: var(--accent);
  font-weight: 650;
}
.question-grid a:hover {
  border-color: var(--accent);
}
.progress-line {
  color: var(--muted);
  font-size: 0.9rem;
  margin: 0 0 14px;
}
.question {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 32px;
  margin-bottom: 24px;
  min-width: 0;
  scroll-margin-top: 24px;
}
.question-meta {
  display: flex;
  gap: 20px;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 18px;
  margin-bottom: 24px;
  border-bottom: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.85rem;
  font-variant-numeric: tabular-nums;
}
.question-id {
  font-weight: 700;
  color: var(--accent);
  overflow-wrap: anywhere;
}
.prompt {
  font-size: 1.15rem;
  line-height: 1.8;
  margin-bottom: 24px;
  max-width: 70ch;
  overflow-wrap: anywhere;
}
.prompt .zh {
  font-size: 1rem;
  margin-top: 12px;
}
.options {
  padding-left: 28px;
  margin-block: 12px 24px;
}
.options li {
  padding-left: 8px;
}
.paper-instruction {
  border-top: 1px dashed var(--border);
  padding-top: 24px;
  margin-top: 28px;
  font-size: 0.9rem;
  color: var(--muted);
}
.question-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 20px;
  justify-content: space-between;
  align-items: center;
  margin-top: 20px;
}
.answer-space {
  display: none;
}
pre,
.table-scroll,
.diagram-scroll {
  max-width: 100%;
  overflow-x: auto;
  overscroll-behavior-inline: contain;
  border: 1px solid var(--border);
  border-radius: 8px;
  margin-block: 20px;
  background: var(--surface);
}
pre {
  padding: 20px;
  color: var(--ink);
  font-size: 0.95rem;
  line-height: 1.8;
  tab-size: 2;
}
code {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}
table {
  border-collapse: collapse;
  min-width: 100%;
  font-size: 0.9rem;
}
th,
td {
  text-align: left;
  vertical-align: top;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
}
th {
  background: var(--subtle);
  font-weight: 650;
}
tr:last-child td {
  border-bottom: 0;
}
.answer-guide {
  max-width: 900px;
  margin-inline: auto;
}
.solution {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  margin-bottom: 16px;
  min-width: 0;
  scroll-margin-top: 24px;
}
.solution summary {
  padding: 22px 26px;
  cursor: pointer;
  color: var(--accent);
  font-weight: 650;
  overflow-wrap: anywhere;
}
.solution summary > span + span {
  margin-left: 16px;
  font-weight: 400;
  font-size: 0.9rem;
}
.solution summary .zh {
  display: inline;
  margin-left: 10px;
}
.solution[open] summary {
  border-bottom: 1px solid var(--border);
}
.solution-inner {
  padding: 28px;
  min-width: 0;
}
.solution-inner h3 {
  margin-top: 28px;
}
.answer {
  background: var(--accent-soft);
  border: 1px solid var(--border);
  padding: 20px 24px;
  border-radius: 8px;
  margin-block: 24px;
  overflow-wrap: anywhere;
}
.answer h3 {
  margin-top: 0;
  color: var(--accent);
}
.answer p {
  margin-bottom: 0;
}
.solution-steps li {
  margin-top: 18px;
  padding-left: 8px;
}
.trap {
  background: var(--warn-bg);
  color: var(--warn);
  border: 1px solid var(--warn);
  border-radius: 8px;
  padding: 18px 22px;
  margin-block: 24px;
}
.trap .zh {
  color: inherit;
}
.trap p {
  margin: 10px 0 0;
}
.rubric {
  list-style: none;
  padding: 0;
}
.rubric li {
  display: flex;
  gap: 20px;
  justify-content: space-between;
  border-bottom: 1px solid var(--border);
  padding: 10px 0;
}
.rubric strong {
  white-space: nowrap;
  font-variant-numeric: tabular-nums;
}
.diagram {
  margin: 28px 0;
}
.diagram svg {
  display: block;
  width: 100%;
  min-width: 560px;
}
.diagram-scroll {
  background: var(--surface);
  padding: 12px;
}
.flow-node rect,
.flow-node path {
  fill: var(--subtle);
  stroke: var(--accent);
  stroke-width: 1.7;
}
.flow-node text {
  fill: var(--ink);
  font-size: 13px;
  font-weight: 550;
}
.edge {
  stroke: var(--muted);
  stroke-width: 1.5;
  fill: none;
}
.edge-label {
  fill: var(--ink);
  font-size: 13px;
  font-weight: 650;
}
.arrow {
  fill: var(--muted);
}
figcaption {
  font-size: 0.9rem;
  color: var(--muted);
  margin-top: 12px;
}
.frame-layout {
  max-width: 600px;
}
.frame-layout svg {
  min-width: 500px;
  border: 1px solid var(--border);
}
.frame-layout rect {
  stroke: var(--border);
  stroke-width: 1.5;
}
.frame-layout text {
  fill: var(--ink);
  font-size: 15px;
}
.banner-region {
  fill: var(--accent-soft);
}
.menu-region {
  fill: var(--subtle);
}
.content-region {
  fill: var(--surface);
}
.pixel-answer {
  font-size: 1.4rem;
  line-height: 1.4;
  letter-spacing: 0.12em;
}
.exam-instructions {
  max-width: 850px;
  margin-bottom: 28px;
}
.exam-instructions li {
  margin-block: 14px;
}
.timer-bar {
  border: 1px solid var(--accent);
  border-radius: var(--radius);
  background: var(--surface);
  padding: 24px 28px;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 14px 24px;
  margin-block: 32px;
}
.timer-bar output {
  display: block;
  font-size: 2.4rem;
  line-height: 1.3;
  color: var(--accent);
  font-weight: 650;
  font-variant-numeric: tabular-nums;
}
.timer-bar > p,
.timer-bar > [data-finish-confirm],
.timer-bar > [data-exam-done] {
  grid-column: 1 / -1;
  margin: 0;
}
.timer-bar [data-deadline] {
  display: block;
  margin-top: 5px;
}
.timer-bar[data-exam-state="expired"] {
  border-color: var(--warn);
}
.timer-bar[data-exam-state="expired"] output {
  color: var(--warn);
}
.exam-dock {
  position: fixed;
  z-index: 10;
  bottom: 16px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 6px;
  padding: 6px;
  border: 1px solid var(--accent);
  border-radius: 12px;
  background: var(--surface);
  box-shadow: var(--shadow);
}
.exam-dock a {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-width: 44px;
  min-height: 44px;
  padding-inline: 10px;
  text-decoration: none;
  font-variant-numeric: tabular-nums;
  font-weight: 650;
}
.dock-label {
  font-size: 0.75rem;
  font-weight: 400;
}
.dock-label .zh {
  display: none;
}
body[data-mock-page] {
  padding-bottom: 80px;
}
html {
  scroll-padding-bottom: 100px;
}
@media print {
  .exam-dock {
    display: none !important;
  }
}
.exam-paper {
  max-width: 900px;
  margin-inline: auto;
}
.exam-section {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 2px solid var(--ink);
  padding-block: 20px 12px;
  margin-block: 32px 24px;
}
.exam-section h2 {
  margin: 0;
}
.exam-section > span {
  color: var(--muted);
  font-size: 0.9rem;
}
.revision-list {
  list-style: none;
  padding: 0;
}
.revision-list li {
  padding-block: 20px;
  border-bottom: 1px solid var(--border);
}
.revision-list p {
  margin: 10px 0 0;
  font-size: 0.95rem;
}
.revision-list li > a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  font-weight: 650;
}
.revision-list {
  max-width: 800px;
}
.revision-list button {
  margin-top: 12px;
}
.storage-warning {
  position: sticky;
  top: 0;
  z-index: 30;
  margin: 0 auto;
  max-width: 1116px;
  padding: 12px 20px;
  background: var(--warn-bg);
  color: var(--warn);
  border: 1px solid var(--warn);
  border-radius: 8px;
}
.storage-warning .zh {
  color: inherit;
}
@media (prefers-reduced-motion: no-preference) {
  .question:not([hidden]) {
    animation: appear 160ms ease-out;
  }
  @keyframes appear {
    from {
      opacity: 0.65;
      transform: translateY(3px);
    }
    to {
      opacity: 1;
      transform: none;
    }
  }
}
@media (max-width: 960px) {
  .site-header {
    flex-wrap: wrap;
    gap: 12px 24px;
    padding-inline: 24px;
  }
  .site-header nav {
    order: 3;
    width: 100%;
    justify-content: center;
    margin: 0;
    border-top: 1px solid var(--border);
  }
  .preferences {
    margin-left: auto;
  }
  main,
  body > footer {
    padding-inline: 24px;
  }
  .home-intro {
    gap: 30px;
    padding-block: 40px;
  }
  .home-intro h1 {
    font-size: 2.2rem;
  }
  .paper-note {
    padding: 24px;
  }
  .workbook {
    grid-template-columns: 176px minmax(0, 1fr);
    gap: 24px;
  }
  .question-grid {
    grid-template-columns: repeat(4, 1fr);
  }
  .question {
    padding: 24px;
  }
  .chapter-grid {
    gap: 24px;
  }
  .row-end {
    display: none;
  }
  .topic-row {
    grid-template-columns: 24px minmax(0, 1fr);
  }
  .mock-card {
    gap: 16px;
    padding: 24px;
  }
}
@media (max-width: 680px) {
  h1,
  .home-intro h1,
  .page-intro h1 {
    font-size: 2rem;
  }
  h2 {
    font-size: 1.4rem;
  }
  main,
  body > footer {
    padding-inline: 18px;
  }
  .site-header {
    padding: 12px 18px 0;
  }
  .site-header nav {
    gap: 20px;
    justify-content: space-between;
  }
  .site-header nav a {
    font-size: 0.8rem;
  }
  .home-intro,
  .chapter-grid,
  .mock-grid,
  .workbook {
    grid-template-columns: minmax(0, 1fr);
  }
  .home-intro {
    gap: 26px;
    padding-block: 32px;
  }
  .paper-note {
    padding: 22px;
  }
  .section-heading {
    display: block;
  }
  .section {
    padding-block: 24px;
  }
  .question-rail {
    position: static;
  }
  .workbook {
    gap: 18px;
  }
  .question-picker > summary {
    display: list-item;
    min-height: 44px;
    padding: 10px 0;
    cursor: pointer;
    border-bottom: 1px solid var(--border);
  }
  .question-picker > summary .ms,
  .question-picker > summary .zh {
    display: inline;
    margin-right: 10px;
  }
  .question-picker > summary [data-picker-current] {
    white-space: nowrap;
    color: var(--muted);
  }
  .question-grid {
    grid-template-columns: repeat(5, 1fr);
    gap: 4px;
    margin-bottom: 10px;
  }
  .question-picker > p:first-of-type {
    margin-bottom: 12px;
  }
  .question-picker > button {
    width: auto;
    margin-right: 10px;
  }
  .question {
    padding: 20px;
  }
  .question-meta {
    margin-bottom: 18px;
  }
  .prompt {
    font-size: 1.05rem;
  }
  .prompt .zh {
    font-size: 0.95rem;
  }
      .question-actions {
    flex-direction: column;
    align-items: stretch;
  }
  .question-actions > * {
    width: 100%;
  }
  .timer-bar {
    grid-template-columns: 1fr;
    padding: 22px;
  }
  .timer-bar > .actions {
    justify-content: flex-start;
  }
  .solution summary {
    padding: 20px;
  }
  .solution summary > span + span {
    display: block;
    margin: 8px 0 0;
  }
  .solution summary .zh {
    display: block;
    margin: 5px 0 0;
  }
  .solution-inner {
    padding: 20px;
  }
  .answer,
  .trap {
    padding: 16px;
  }
  .review-banner {
    padding: 26px 0;
  }
  .mock-letter {
    font-size: 2.5rem;
  }
  pre {
    font-size: 0.85rem;
    padding: 16px;
  }
}
@media print {
  :root,
  :root[data-theme="dark"] {
    color-scheme: light;
    --background: white;
    --surface: white;
    --subtle: #f2f2f2;
    --ink: black;
    --muted: #333;
    --border: #aaa;
    --accent: #17483f;
    --accent-soft: #f2f2f2;
    --warn: #333;
    --warn-bg: #f4f4f4;
  }
  body {
    background: white;
    font-size: 11pt;
  }
  main,
  body > footer {
    width: 100%;
    padding: 0;
  }
  .site-header,
  .question-rail,
  .question-actions,
  .actions,
  .timer-bar,
  .back,
  .skip,
  .storage-warning,
  noscript,
  button,
  .progress-line {
    display: none !important;
  }
  .page-intro {
    padding-block: 0 12px;
  }
  .page-intro h1 {
    font-size: 22pt;
  }
  .workbook {
    display: block;
  }
  .question[hidden] {
    display: block !important;
  }
  .question {
    border: 0;
    border-radius: 0;
    border-top: 1px solid #888;
    padding: 18px 0;
    break-inside: avoid;
    box-shadow: none;
  }
  .question-meta {
    margin-bottom: 12px;
    padding-bottom: 0;
    border: 0;
  }
  .question .answer-space {
    display: block;
    min-height: 60px;
  }
  .paper-instruction {
    display: none;
  }
  .solution {
    border: 0;
    border-top: 1px solid #888;
    border-radius: 0;
  }
  .solution-inner {
    padding: 10px 0;
  }
  .solution summary {
    padding: 15px 0;
  }
  .solution summary > span + span {
    display: none;
  }
  .diagram-scroll,
  .table-scroll,
  pre {
    overflow: visible;
    max-width: 100%;
  }
  pre {
    white-space: pre-wrap;
    overflow-wrap: anywhere;
  }
  .diagram {
    break-inside: avoid;
  }
  .diagram svg {
    min-width: 0;
    max-height: 215mm;
  }
  .exam-section {
    break-after: avoid;
  }
  .answer-guide {
    max-width: none;
  }
  .home-intro,
  .mock-grid {
    display: block;
  }
  a {
    color: #17483f;
  }
  @page {
    margin: 16mm;
  }
}

/* A reading route, with the next action always within reach. */
.site-header { gap: 22px; }
.site-header nav { gap: 18px; }
.site-header nav a { min-height: 44px; }
.site-header nav .zh { font-size: 0.75rem; margin-top: 2px; }
.chapter-jumps, .resume-links { display: flex; flex-wrap: wrap; gap: 10px; }
.chapter-jumps { margin-bottom: 28px; }
.resume-links:has(.resume-link:not([hidden])) { margin-block: 14px 24px; }
.resume-link { text-align: left; }
.study-intro { padding-block: 26px 20px; }
.study-intro h1 { margin-top: 12px; }
.keyboard-hint { color: var(--muted); font-size: 0.8rem; margin-bottom: 0; }
.keyboard-hint .zh { font-size: inherit; }
body[data-study-page] { padding-bottom: 110px; }
.practice-dock {
  position: fixed; z-index: 20; bottom: 0; left: 0; right: 0;
  display: grid; grid-template-columns: minmax(0,1fr) auto minmax(0,1fr);
  align-items: center; gap: 20px;
  padding: 12px max(24px, calc((100vw - 920px) / 2));
  background: var(--surface); border-top: 1px solid var(--border);
}
.practice-dock button:first-child { justify-self: start; }
.practice-dock button:last-child { justify-self: end; }
.practice-dock .progress-line { margin: 0; text-align: center; }
.practice-dock .progress-line .zh { margin-top: 4px; }
.set-end { padding-block: 12px; }
.answer-select { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; margin: 18px 0; }
.answer-select select {
  min-width: 0; max-width: 100%; min-height: 44px; padding: 9px 12px;
  background: var(--surface); color: var(--ink); border: 1px solid var(--border); border-radius: 6px; font: inherit;
}
.easy-answer { margin: 28px 0; padding-block: 20px; border-block: 1px solid var(--border); }
.easy-answer h3 { color: var(--accent); margin-top: 0; }
.easy-answer p { max-width: 65ch; }
.solution { scroll-margin-block: 20px 110px; }
.focus-sets { max-width: 960px; margin: 0 auto 32px; }
.focus-set { padding: 26px 0; border-top: 1px solid var(--border); display: grid; grid-template-columns: minmax(0,1fr) auto; gap: 16px 30px; }
.focus-set-description { display: flex; align-items: start; gap: 20px; }
.set-number { font-size: 1.4rem; color: var(--accent); font-weight: 700; min-width: 24px; }
.focus-set h2 { margin-top: 0; font-size: 1.4rem; }
.focus-set-description p { margin-bottom: 8px; max-width: 56ch; }
.focus-set-actions { display: flex; flex-direction: column; align-items: start; gap: 12px; }
.focus-contents { grid-column: 1 / -1; margin-left: 44px; }
.focus-contents summary { min-height: 44px; cursor: pointer; padding-block: 10px; color: var(--accent); }
.focus-contents summary .ms, .focus-contents summary .zh { display: inline; margin-right: 12px; }
.focus-contents li { padding: 8px 0; }
.focus-contents li > .small { display: block; color: var(--muted); margin-top: 4px; }
.focus-contents a { display: inline-flex; gap: 12px; flex-wrap: wrap; min-height: 44px; align-items: center; }
.focus-contents a .zh { margin: 0; }
@media (max-width: 960px) {
  .site-header nav { justify-content: space-between; }
  .home-intro { padding-top: 28px; }
}
@media (max-width: 680px) {
  .site-header nav { gap: 8px; }
  .site-header nav a { font-size: 0.74rem; }
  .site-header nav .zh { font-size: 0.66rem; }
  .study-intro { padding-top: 18px; }
  .study-intro h1 { font-size: 1.75rem; }
  .focus-set { grid-template-columns: minmax(0,1fr); }
  .focus-set-actions { margin-left: 44px; flex-direction: row; align-items: center; flex-wrap: wrap; }
  .practice-dock { padding: 10px 12px; gap: 8px; }
  .practice-dock button { padding: 8px 10px; flex-direction: column; gap: 2px; font-size: 0.83rem; }
  .practice-dock button .zh { margin: 0; }
  .practice-dock .progress-line { font-size: 0.76rem; }
  .practice-dock .progress-line .zh { font-size: 0.7rem; }
  .answer-select { display: block; }
  .answer-select select { width: 100%; margin-top: 8px; }
}
@media print {
  body[data-study-page] { padding-bottom: 0; }
  .practice-dock, .keyboard-hint, .answer-select, .resume-links, .set-end { display: none !important; }
  .solution[hidden] { display: block !important; }
  .easy-answer { break-inside: avoid; }
}

.paper-pager { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 24px; }
@media print { .paper-pager { display: none !important; } }