:root {
  color-scheme: light;
  --ink: #1f2933;
  --muted: #66727f;
  --line: #d8dee5;
  --paper: #fff;
  --canvas: #f4f5f7;
  --accent: #174a68;
}

* {
  box-sizing: border-box;
}

html {
  background: var(--canvas);
}

body {
  margin: 0;
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}

.page-shell {
  width: min(100% - 32px, 1100px);
  margin: 0 auto;
  padding: 34px 0 28px;
}

.site-header {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 22px;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0;
}

h1 {
  max-width: 760px;
  margin: 0;
  font-family: Georgia, "Songti SC", "STSong", serif;
  font-size: clamp(24px, 3vw, 38px);
  line-height: 1.2;
  letter-spacing: 0;
}

.download-link {
  flex: 0 0 auto;
  padding: 10px 14px;
  border: 1px solid var(--accent);
  border-radius: 5px;
  color: var(--accent);
  font-size: 14px;
  text-decoration: none;
  white-space: nowrap;
}

.download-link:hover,
.download-link:focus-visible {
  color: #fff;
  background: var(--accent);
}

.paper-frame {
  overflow: auto;
  padding: 24px;
  border: 1px solid var(--line);
  background: #e9ecef;
  box-shadow: 0 10px 28px rgb(31 41 51 / 10%);
}

.paper-frame img {
  display: block;
  width: min(100%, 882px);
  height: auto;
  margin: 0 auto;
  background: var(--paper);
  box-shadow: 0 2px 12px rgb(31 41 51 / 12%);
}

.site-footer {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 16px 2px 0;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.5;
}

@media (max-width: 640px) {
  .page-shell {
    width: min(100% - 20px, 1100px);
    padding-top: 20px;
  }

  .site-header {
    align-items: start;
    flex-direction: column;
    gap: 14px;
  }

  .download-link {
    padding: 9px 12px;
  }

  .paper-frame {
    padding: 8px;
  }

  .paper-frame img {
    width: 882px;
    max-width: none;
  }

  .site-footer {
    flex-direction: column;
    gap: 4px;
  }
}