:root {
  --ink: #171a17;
  --muted: #646a64;
  --bg: #f6f5f1;
  --panel: #ffffff;
  --line: #d9d5cc;
  --active: #235f46;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans TC", "PingFang TC", sans-serif;
  line-height: 1.65;
  overflow-x: hidden;
}

h1,
h2,
h3,
p,
button strong {
  overflow-wrap: anywhere;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 18px clamp(18px, 4vw, 48px);
  background: rgba(246, 245, 241, 0.96);
  border-bottom: 1px solid var(--line);
}

h1 {
  margin: 0;
  font-size: clamp(28px, 4vw, 40px);
  letter-spacing: 0;
}

nav {
  display: flex;
  gap: 8px;
}

nav a {
  padding: 10px 14px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--panel);
  color: var(--ink);
  text-decoration: none;
  font-size: 18px;
}

.viewer-page .topbar {
  align-items: center;
}

main {
  width: min(1280px, 100%);
  margin: 0 auto;
  padding: 28px clamp(16px, 4vw, 48px) 56px;
}

.section {
  margin-bottom: 46px;
}

h2 {
  margin: 0 0 16px;
  font-size: clamp(34px, 5vw, 48px);
  letter-spacing: 0;
}

.button-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin-bottom: 14px;
}

button,
.doc-link {
  width: 100%;
  min-width: 0;
  min-height: 110px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--panel);
  color: var(--ink);
  text-align: left;
  font: inherit;
  cursor: pointer;
}

.viewer-main {
  width: 100%;
  max-width: none;
  padding: 12px;
}

.pdf-status {
  padding: 18px;
  color: var(--muted);
  font-size: 20px;
}

.pdf-pages {
  display: grid;
  gap: 14px;
  justify-items: center;
}

.pdf-page {
  width: min(100%, 1100px);
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #fff;
}

.pdf-page canvas {
  display: block;
  max-width: 100%;
  height: auto !important;
}

button span {
  display: block;
  margin-bottom: 5px;
  color: var(--active);
  font-size: 20px;
  font-weight: 800;
}

button strong,
.doc-link strong {
  display: block;
  font-size: clamp(22px, 2.4vw, 28px);
  line-height: 1.28;
}

button.active {
  border-color: var(--active);
  background: #e8f1ea;
}

.answer-panel {
  padding: clamp(18px, 3vw, 30px);
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
}

.panel-label {
  color: var(--active);
  font-weight: 900;
  font-size: 22px;
}

.answer-panel h3 {
  margin: 4px 0 18px;
  font-size: clamp(30px, 4vw, 44px);
  line-height: 1.25;
  letter-spacing: 0;
}

.answer-panel p {
  margin: 0 0 14px;
  font-size: clamp(22px, 2.7vw, 30px);
}

.doc-link {
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--ink);
  text-decoration: none;
}

.doc-link {
  min-height: 86px;
  text-align: center;
}

.doc-link strong {
  font-size: clamp(24px, 2.8vw, 32px);
}

@media (max-width: 760px) {
  .topbar {
    align-items: flex-start;
    flex-direction: column;
  }

  .button-grid {
    grid-template-columns: minmax(0, 1fr);
    gap: 12px;
  }

  main {
    padding-inline: 14px;
  }

  button {
    min-height: 104px;
  }

  button strong {
    font-size: 21px;
  }

  .answer-panel h3 {
    font-size: 29px;
  }

  .answer-panel p {
    font-size: 21px;
  }

  .doc-link {
    min-height: 96px;
  }

  .viewer-page .topbar {
    position: sticky;
    align-items: flex-start;
  }

  .viewer-main {
    padding: 10px 8px;
  }
}