Floating logo over small top bar

i’ve made an floating logo in the site http://146.66.86.14/~wetensch/americol.nl/

I used:

.logo, .logo a {
overflow: visible;
}
.logo img {
max-height: 140px !important;
}
Is there a way to position the logo also over the small top bar? I can do it with negative padding/margin but is does’nt work well in the mobile resposive view. It also hides under the topbat so i have to do something with z-index i guess.