CSS issue in IE8

I have a css navigation menu in my theme that works great in all browsers except IE8. for some reason, in IE8, the final li in the menu is dropping down lower than all the other li’s. here’s a screenshot of what it looks like: https://screencast.com/t/2dNJfLtSQH

the css for the menu is pretty straightforward:

#nav-primary ul, #nav-primary li {
	list-style: none;
	display: inline;

}
#nav-primary ul {
	margin: 0;
	padding: 0 0 0 7%;
	font-family: FontinSans;
	font-size: 125%;
}
#nav-primary ul li a {
	padding: 0.2em 12px;
	color: #000000;
	text-decoration: none;
	float: left

has anyone come across this issue before? the URL is https://test.stashknitrepeat.com

thanks!