Improve the appearance on the history page

Make the revision-compare button level with buttons on the right side;
Improve the specificity of rules, make hovered styles of buttons on the history page consistent.

Change-Id: I0832da75a3d2624793692fd495ab6e723a079309

resources/forms.less

@@ -6,8 +6,8 @@ input {
 
 // Because weird special cases that get broken by this usually aren't forms?
 form {
-	// Special-case out the datetime widget
-	input:not( .mw-widgets-datetime-dateTimeInputWidget-editField ) {
+	// Special-case out the datetime widget and revision-compare button
+	input:not( .mw-widgets-datetime-dateTimeInputWidget-editField ):not( .mw-history-compareselectedversions-button ) {
 		margin: 0.5em 0;
 		padding: 0.35em;
 	}
@@ -99,8 +99,8 @@ form:not( .oo-ui-layout ) {
 		color: #fff;
 		border: solid 1px #36c;
 
-		&:hover,
-		&:active {
+		&:not( :disabled ):hover,
+		&:not( :disabled ):active {
 			background-color: #47f;
 		}
 	}