Minor aesthetic amend to datepicker prev/next

Author: philwareham

dist/textpattern/jquery-ui.css

@@ -971,9 +971,10 @@ input.ui-button.ui-icon-notext .ui-icon {
 .ui-datepicker .ui-datepicker-prev,
 .ui-datepicker .ui-datepicker-next {
   position: absolute;
-  top: 0.2em;
+  top: 50%;
   width: 1.8em;
   height: 1.8em;
+  margin-top: -0.9em;
   border-radius: 0.5em;
   background-color: transparent;
 }

dist/textpattern/jquery-ui.min.css

@@ -94,9 +94,10 @@
     .ui-datepicker-prev,
     .ui-datepicker-next {
         position: absolute;
-        top: 0.2em;
+        top: 50%;
         width: 1.8em;
         height: 1.8em;
+        margin-top: -0.9em;
         @if $border-radius > 0 {
             border-radius: $border-radius;
         }