Simplify the page controls by dropping the drop shadow

Makes the icons less blurry in Retina™ displays

themes/tiddlywiki/snowwhite/base.tid

@@ -331,17 +331,15 @@ a.tw-tiddlylink-external {
 }
 
 .tw-page-controls svg {
-	height: 1.5em;
+	height: 1.75em;
 	min-width: 1px;
 	padding-right: 0.5em;
 	fill: #fff;
-	<<filter "drop-shadow(1px 1px 2px rgba(0,0,0,0.15))">>
 	<<transition "fill 150ms ease-in-out">>
 }
 
 .tw-page-controls svg:hover {
 	fill: #000;
-	<<filter "drop-shadow(1px 1px 2px rgba(255,255,255,0.9))">>
 }
 
 .tw-menu-list-item {