This was my mis-behaving code:

#rightmasthead, #leftmasthead {
float:right;
text-align: right;
margin: 33px 0;
padding: 10px 15px 0 0;
border:0px solid #000;
width: 300px;
}

Personally, I try to avoid using CSS hacks, and when writing client code I always assume that anything can be done the “proper” way.

However, in most cases a hack is useful and needed, so here are two hacks (which are, in fact a valid CSS) that can be used to target and distinguish Google Chrome and Safari:

@media screen and (-webkit-min-device-pixel-ratio:0) {
#rightmasthead, #leftmasthead {
margin: 32px 0; /* This works only in Safari and Google Chrome */
}
}

Viola it works now perfectly!