Remove background from blockquotes

This looks odd in dark mode, and isn't super necessary anyway

static/src/scss/_bulma_overrides.scss

@@ -8,6 +8,7 @@ $dropdown-content-offset: 0;
 $primary: #e85537;
 $link: $primary;
 $dark: #17181c;
+$content-blockquote-background-color: transparent;
 
 // Navbar overrides
 $navbar-item-color: $grey-light;