Tjalling.

I fixed the problem!
Thanks, both of you.

It had a little delay to appear correctly on IE.

If anyone who’s using Safari (20% of my visitor are using it) could check out my site and tell me if it’s working.

Would be great!

Thanks for the reactions!

I did change the original sizes to 1014 x 180 now.
It’s about the only size that will display it correctly in Google Chrome.

Still,

The other browsers don’t display it correctly.

I found this in the css:

.themonic-logo {
padding: 17px;
float:left;
margin:10px 0;
}

and this:

/* Logo responsiveness in case of big logos */
.themonic-logo img {
max-width: 100%;

and the last piece:

.themonic-logo {
float: none;
margin: 0 0 10px;

Could it be of any use? (Note, I know basically nothing about coding etc.)