jquery-ui/themes/base/ui.core.css

/*
* jQuery UI CSS Framework
* Copyright (c) 2008 AUTHORS.txt (http://ui.jquery.com/about)
* Dual licensed under the MIT (MIT-LICENSE.txt) and GPL (GPL-LICENSE.txt) licenses.
*/

/* Layout helpers
----------------------------------*/
.ui-helper-hidden { display: none; }
.ui-helper-hidden-accessible { position: absolute; left: -99999999px; }
.ui-helper-reset { margin: 0; padding: 0; border: 0; outline: 0; line-height: 1.3; text-decoration: none; font-size: 100%; list-style: none; }

.ui-helper-clearfix:after { content: "."; display: block; height: 0; clear: both; visibility: hidden; }
.ui-helper-clearfix { display: inline-block; }

/* DO NOT REMOVE THIS COMMENT - required for clearfix to work in Opera \*/
* html .ui-helper-clearfix { height:1%; }
.ui-helper-clearfix { display:block; }
/* end required block */

.ui-helper-zfix { width: 100%; height: 100%; top: 0; left: 0; position: absolute; opacity: 0; filter:Alpha(Opacity=0); }