Button: override default margin if controlgroups or form elements hav…

…e class ui-btn-left/right. Fixes #4713 - Controlgroup: Horizontal controlgroup shouldn't have margins in header.

css/structure/jquery.mobile.button.css

@@ -5,6 +5,7 @@
 .ui-btn-inner { font-size: 16px; padding: .6em 20px; min-width: .75em; display: block; position: relative; text-overflow: ellipsis; overflow: hidden; white-space: nowrap; zoom: 1; }
 .ui-btn input, .ui-btn button { z-index: 2; }
 .ui-btn-left, .ui-btn-right, .ui-btn-inline { display: inline-block; vertical-align: middle; }
+.ui-mobile .ui-btn-left, .ui-mobile .ui-btn-right { margin: 0; } /* .ui-mobile to increase specificity level */
 .ui-btn-block { display: block; }
 
 .ui-header .ui-btn,