a11y(darkmode): use a button for the theme toggle (#1335)

Andrew

2024-08-24 4c9e8601504f76dcc3c273ea8ad1862df432b7b4

 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%;