fix: embed pdf aspect ratio (closes #1310)

Jacky Zhao

2024-08-06 3938904cd096205b27741538655c3fb18cd401be

 quartz/styles/base.scss

@@ -542,7 +542,8 @@
  overflow-y: hidden;
}

.external-embed.youtube {
.external-embed.youtube,
iframe.pdf {
  aspect-ratio: 16 / 9;
  height: 100%;
  width: 100%;