Fixes background color in fullscreen mode (#165)

* Fixes background color in fullscreen mode

* Applied fix suggested by @curtgrimes

src/coll.js

@@ -476,6 +476,7 @@ class Coll extends LitElement
       flex-direction: column;
       min-height: 0px;
       flex: auto;
+      background-color: white;
     }
 
     #tabContents {

ui.js

@@ -998,6 +998,7 @@ class se extends oe{}se.directiveName="unsafeSVG",se.resultType=2;const le=ae(se
       flex-direction: column;
       min-height: 0px;
       flex: auto;
+      background-color: white;
     }
 
     #tabContents {