A few miscellaneous style fixes

- Add some padding to the top of the footnotes block
- Add .figure--video to the list of elements that get XL block margins

layouts/_default/_markup/render-image.html

@@ -1,5 +1,5 @@
 {{- if .IsBlock }}
-  <figure class="figure figure--image" id="figure-{{ .Ordinal }}">
+  <figure class="figure  figure--image" id="figure-{{ .Ordinal }}">
     <img src="{{ .Destination | safeURL }}"
       {{- with .Text }} alt="{{ . }}"{{ end -}}
     >