:root {
  --bg: #efede7;
  --panel: #ffffff;
  --panel-soft: #faf9f6;
  --line: #ddd8cf;
  --line-strong: #cfc8bc;
  --text: #1f1f1b;
  --text-muted: #555850;
  --link: #1f4d87;
  --shadow: 0 18px 48px rgba(43, 42, 38, 0.06);
  --max-width: 940px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Noto Sans CJK SC", "Microsoft YaHei",
    "Helvetica Neue", Arial, sans-serif;
  --font-serif: "Iowan Old Style", "Palatino Linotype", "Book Antiqua",
    "Times New Roman", "Songti SC", "STSong", serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
}

a {
  color: inherit;
  text-decoration: none;
}

img {
  display: block;
  max-width: 100%;
}

.page-shell {
  width: min(calc(100% - 32px), var(--max-width));
  margin: 32px auto;
  background: var(--panel);
  border: 1px solid var(--line-strong);
  box-shadow: var(--shadow);
}

.page-header {
  padding: 48px 56px 32px;
}

.page-header h1 {
  margin: 0;
  max-width: 16ch;
  font-family: var(--font-serif);
  font-size: clamp(2.4rem, 5vw, 3.5rem);
  line-height: 1.15;
  letter-spacing: -0.02em;
}

.resource-links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 22px;
}

.resource-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 140px;
  padding: 10px 16px;
  border: 1px solid var(--line-strong);
  background: var(--panel);
  color: var(--link);
  font-size: 0.96rem;
  font-weight: 600;
  transition: background 0.2s ease, border-color 0.2s ease;
}

.resource-link:hover {
  border-color: var(--link);
  background: #f5f8fc;
}

.paper-layout {
  display: grid;
}

.paper-section {
  padding: 30px 56px;
  border-top: 1px solid var(--line);
}

.paper-section h2 {
  margin: 0 0 14px;
  font-family: var(--font-serif);
  font-size: 1.45rem;
  font-weight: 700;
}

.paper-section p,
.paper-section figcaption {
  margin: 0;
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1.8;
}

.keyword-list {
  color: var(--text);
}

.section-note {
  max-width: 72ch;
}

.figure-list {
  display: grid;
  gap: 22px;
  margin-top: 22px;
}

.paper-figure {
  margin: 0;
  padding: 18px;
  border: 1px solid var(--line);
  background: var(--panel-soft);
}

.paper-figure img {
  width: 100%;
  border: 1px solid var(--line);
  background: var(--panel);
}

.paper-figure figcaption {
  margin-top: 14px;
}

.paper-figure strong,
.placeholder-box strong {
  color: var(--text);
}

.placeholder-box {
  min-height: 150px;
  padding: 24px;
  border: 1px dashed var(--line-strong);
  background: var(--panel-soft);
  display: flex;
  align-items: center;
}

.cases-panel {
  display: grid;
  gap: 18px;
  margin-top: 20px;
}

.task-switcher {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.task-switch {
  padding: 10px 16px;
  border: 1px solid var(--line-strong);
  background: var(--panel);
  color: var(--text);
  font: inherit;
  cursor: pointer;
  transition: background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.task-switch.is-active,
.task-switch:hover {
  background: #1f4d87;
  border-color: #1f4d87;
  color: #fff;
}

.cases-status,
.cases-intro-text,
.audio-card-subtitle,
.audio-card-text {
  color: var(--text-muted);
}

.cases-intro {
  display: grid;
  gap: 8px;
  padding: 18px;
  border: 1px solid var(--line);
  background: var(--panel-soft);
}

.cases-intro-title,
.case-group-title {
  margin: 0;
  color: var(--text);
  font-family: var(--font-serif);
  font-size: 1.15rem;
}

#cases-root {
  display: grid;
  gap: 22px;
}

.case-group {
  display: grid;
  gap: 14px;
  padding: 18px;
  border: 1px solid var(--line);
  background: var(--panel-soft);
}

.case-grid {
  display: grid;
  gap: 14px;
}

.case-grid-2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

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

.case-grid-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.case-grid-4 {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.task1-five-card-grid {
  display: grid;
  gap: 14px;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  align-items: stretch;
}

.audio-card {
  display: grid;
  gap: 0;
  padding: 10px;
  border: 1px solid var(--line);
  background: var(--panel);
}

.task2-card {
  gap: 0;
  grid-template-rows: auto auto 6rem auto auto;
  align-content: start;
}

.task2-card-zh {
  grid-template-rows: auto auto 5.2rem auto auto;
}

.task2-card-en {
  grid-template-rows: auto auto 7rem auto auto;
}

.task2-card .audio-card-subtitle {
  white-space: nowrap;
  font-size: 0.82rem;
  letter-spacing: -0.015em;
}

.task2-card .audio-card-text {
  height: 6rem;
  overflow: hidden;
  padding-right: 0;
  font-size: 0.84rem;
  line-height: 1.4;
  display: -webkit-box;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 4;
  scrollbar-width: none;
  -ms-overflow-style: none;
}

.task2-card-zh .audio-card-text {
  height: 5.2rem;
}

.task2-card-en .audio-card-text {
  height: 7rem;
}

.task2-card .audio-card-text::-webkit-scrollbar {
  display: none;
}

.task2-card .audio-card-text::-webkit-scrollbar-button {
  display: none;
  visibility: hidden;
  width: 0;
  height: 0;
}

.task2-card .case-pills {
  display: grid;
  margin-top: 8px;
  gap: 6px;
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.task2-card .case-pill {
  padding: 4px 8px;
  font-size: 0.68rem;
  white-space: nowrap;
  min-width: 0;
  overflow: hidden;
  text-overflow: clip;
  text-align: center;
}

.audio-card-label {
  color: var(--text);
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.audio-card-subtitle,
.audio-card-text {
  margin: 0;
  line-height: 1.6;
  font-size: 0.95rem;
}

.audio-player {
  width: 100%;
  min-height: 0;
  line-height: 1;
}

.task1-case-card {
  display: grid;
  grid-template-rows: 2.2rem minmax(52px, auto);
  align-content: start;
  gap: 10px;
  min-height: 112px;
  padding: 12px;
}

.task1-case-card .audio-card-label {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 2.2rem;
  margin: 0;
  color: var(--text);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  line-height: 1.15;
  text-align: center;
  text-transform: uppercase;
}

.task1-case-card .audio-player {
  width: 100%;
  min-width: 0;
  align-self: end;
}

.case-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.case-pill {
  padding: 5px 10px;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--text-muted);
  font-size: 0.82rem;
  line-height: 1.2;
}

.footer {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  padding: 22px 56px 32px;
  border-top: 1px solid var(--line);
  color: var(--text-muted);
  font-size: 0.92rem;
}

@media (max-width: 720px) {
  .page-shell {
    width: min(calc(100% - 20px), var(--max-width));
    margin: 16px auto;
  }

  .page-header,
  .paper-section,
  .footer {
    padding-left: 24px;
    padding-right: 24px;
  }

  .page-header {
    padding-top: 28px;
    padding-bottom: 24px;
  }

  .paper-section {
    padding-top: 24px;
    padding-bottom: 24px;
  }

  .resource-link {
    width: 100%;
  }

  .placeholder-box {
    min-height: 120px;
  }

  .case-grid-2,
  .case-grid-3,
  .case-grid-4 {
    grid-template-columns: 1fr;
  }
}