That is because the div unibar_container has a width of 1002px while everything else in the page is clamped at 992px.
So a simple workaround for this is replacing:
.unibar_container { width: 1002px; -> change that to 992px
margin: 0 auto;
}
--------------------------------------- OLD CONTENT ---------------------------------------------
Hi,
I know it mustn't be the right section for that but the web programmers should add min-width: 992px; attribute to the body of the main site homepage, because the content bar is clamped at 992px while the header isn't, so when you have a browser width inferior to 992px you get this: