Firefoxでおこるバグ回避のクラスpkg

Firefoxでおこるバグ回避のクラス

class="pkg"

/* .pkg class wraps enclosing block element around inner floated elements
-------------------------------------------------------------------------------- */
/* for modern browser */
.pkg {
overflow: hidden;
}

.pkg:after {
content: ".";
display: block;
height: 1px;
clear: both;
overflow: hidden;
}

/* Hides from IE-mac \*/
* html .pkg {
height: 1em;
overflow: visible;
}
/* End hide from IE-mac */