we already tried to check this for you but we can't because you don't have menu. Instead all we see is warning related with the plugin http://pbrd.co/1EoN631
Sorry I was trying to look for Where does the problem is visible because of a class: * *: before, *: after {-webkit-box-sizing: border-box; -moz- box-sizing: border-box; box-sizing: border-box on my account customer plugin aera.
It classifies pourait I add to the menu so that the two work together?
Now your menu works so we can check. We tried to replicate this problem and we are pretty sure that the problem is related with not enough space in header because of too many items. So or you will remove one of the items in menu (and move into submenu instead) or you will use below css to decrease padding between menu items:
#Top_bar .menu > li > a span:not(.description) { padding: 0 15px; }
Comments
we already tried to check this for you but we can't because you don't have menu. Instead all we see is warning related with the plugin http://pbrd.co/1EoN631