Margin auto fails IE11

it doesn't work because the max-width;

Try this:

.bg-content {
    width: 605px;
    height: 149px;
    position: absolute;
    top: 62px;
    font-family: sans-serif;
    margin-left: auto;
    margin-right: auto;
    left: 0;
    right: 0;
}

for a fixed position element :

left: 0;
right: 0:
width: 100%;
margin: 0 auto; 

You should use

width: 100%;

in your .bg-content element

Example: IE11 max-width & margin auto fix

The hack I always use for Internet Explorer (mostly for the older versions though), is setting the parent container text-align: center; and the container itself text-align: left;.

I have taken a look at your website, and the parent container seems to not have a default width. Please try setting it on width: 100%;. I tried that in the run-time environment, and it seemed to work.