This works nicely for me:
<style>a.closeX { position: absolute; right: 0px; top: 0px; width:20px; background-color: #FFF; color: black; margin-top:-15px; margin-right:-15px; border-radius: 20px; padding-left: 3px; padding-top: 1px; cursor:pointer; z-index: -1; font-size:16px; font-weight:bold;}</style><div id="content"><a class="closeX" id="closeX" onclick='$("#content").hide();'>✖</a> Click "X" to close this box</div>