overlay-core.css

/*
YUI 3.7.3 (build 5687)
Copyright 2012 Yahoo! Inc. All rights reserved.
Licensed under the BSD License.
http://yuilibrary.com/license/
*/
.yui3-overlay {
    position:absolute;
}

.yui3-overlay-hidden {
    visibility:hidden
}

.yui3-widget-tmp-forcesize .yui3-overlay-content {
    overflow:hidden !important;
}