examples: fix dark theme on empty location hash (#21932)

Co-authored-by: NFelix Mariotto <felixmariotto@gmail.com>

examples/index.html

@@ -118,6 +118,7 @@
 
 					selectFile( file );
 					viewer.src = validRedirects.get( file );
+					viewer.style.display = 'unset';
 
 				}
 
@@ -234,6 +235,7 @@
 
 			window.location.hash = file;
 			viewer.focus();
+			viewer.style.display = 'unset';
 
 			panel.classList.remove( 'open' );
 

files/main.css

@@ -383,6 +383,7 @@ iframe {
 	width: 100%;
 	height: 100%;
 	overflow: auto;
+	display: none;
 }
 
 #viewer {