Move the modal background blur effect from Snow White to Vanilla

It’s a slow effect, and so it should be possible to suppress it by
returning to the barebones Vanilla theme.

themes/tiddlywiki/snowwhite/base.tid

@@ -107,6 +107,10 @@ canvas.tw-edit-bitmapeditor  {
 	<<box-shadow "2px 2px 10px rgba(0, 0, 0, 0.5)">>
 }
 
+.tw-modal-displayed {
+	-webkit-filter: blur(4px);
+}
+
 .modal {
 	<<border-radius 6px>>
 	<<box-shadow "0 3px 7px rgba(0,0,0,0.3)">>

themes/tiddlywiki/vanilla/base.tid

@@ -732,10 +732,6 @@ canvas.tw-edit-bitmapeditor  {
 ** Modals
 */
 
-.tw-modal-displayed {
-	-webkit-filter: blur(4px);
-}
-
 .modal-backdrop {
 	position: fixed;
 	top: 0;