fix(web): Revert prevent flashing white background in dark mode on page load/reload (#19934) (#20122)

Revert "fix(web): prevent flashing white background in dark mode on page load/reload (#19934)"

This reverts commit 32f23b8.

Author: alextran1502

web/src/app.html

@@ -21,11 +21,6 @@
       html {
         height: 100%;
         width: 100%;
-        background-color: rgb(255, 255, 255);
-      }
-
-      html.dark {
-        background-color: rgb(10, 10, 10);
       }
 
       body,
@@ -34,10 +29,6 @@
         padding: 0;
       }
 
-      body {
-        transition: background-color 0.15s ease;
-      }
-
       @keyframes delayedVisibility {
         to {
           visibility: visible;