jQuery
var stickyElement = $( "#list-faq-wrap" );
var stickyElementPos = stickyElement.offset();
$( window ).scroll( function () {
var windowpos = $( window ).scrollTop();
if ( windowpos >= stickyElementPos.top - 20 ) {
stickyElement.addClass( "stick" );
} else {
stickyElement.removeClass( "stick" );
}
} );
CSS
.stick {
position: fixed;
top: 0;
z-index: 999;
}