img, video are max-width 100% otherwise centered and kept in original dimensions

assets/css/site.css

@@ -477,8 +477,11 @@ ol li {
   list-style-type: decimal;
 }
 
-img {
+img, video {
-  width: 100%;
+  max-width: 100%;
+  display: block;
+  margin-left: auto;
+  margin-right: auto;
 }
 
 .supt {

layouts/_default/_markup/render-image.html

@@ -9,12 +9,12 @@
   {{- $img_params := (substr .Destination 4) -}}
   {{- $img_src := index (split $img_params " ") 0 -}}
   {{- $img_attr := index (split $img_params $img_src) 1 -}}
-<img src="{{ $img_src }}" {{ $img_attr | safeHTMLAttr }} />
+<img class="sandpoints-img" src="{{ $img_src }}" {{ $img_attr | safeHTMLAttr }} />
 {{- else if strings.HasPrefix .Destination "vid:" -}}
   {{- $vid_params := (substr .Destination 4) -}}
   {{- $vid_src := index (split $vid_params " ") 0 -}}
   {{- $vid_attr := index (split $vid_params $vid_src) 1 -}}
-<video controls src="{{ $vid_src }}" {{ $vid_attr | safeHTMLAttr }}></video>
+<video class="sandpoints-vid" controls src="{{ $vid_src }}" {{ $vid_attr | safeHTMLAttr }}></video>
 {{- else if strings.HasPrefix .Destination "bib:" -}}
   {{- $destination := (substr .Destination 4) -}}
   {{- $c_prefix := .Page.Site.Params.sandpointsCatalogPrefix | default "/library/" -}}