Fix loading indicator

services/web/public/stylesheets/app/editor.less

@@ -91,7 +91,7 @@
 				right: 0;
 				bottom: 0;
 				left: 0;
-				background: @editor-loading-logo-background-url no-repeat bottom / 100%;
+				background: @editor-loading-logo-foreground-url no-repeat bottom / 100%;
 				transition: height .5s;
     		}
 		}

services/web/public/stylesheets/core/ol-variables.less

@@ -30,5 +30,6 @@
 
 @editor-loading-logo-padding-top: 115.44%;
 @editor-loading-logo-background-url: url(/img/ol-brand/overleaf-o-grey.svg);
+@editor-loading-logo-foreground-url: url(/img/ol-brand/overleaf-o.svg);
 
 @import "./_common-variables.less";

services/web/public/stylesheets/core/variables.less

@@ -27,5 +27,6 @@
 
 @editor-loading-logo-padding-top: 86.2%;
 @editor-loading-logo-background-url: url(/img/brand/lion-grey.svg);
+@editor-loading-logo-foreground-url: url(/img/brand/lion.svg);
 
 @import "_common-variables.less";