adaliabooks: I'm not sure. I know there are various CSS modifications for the website floating about that different users use but I don't ever remember seeing a thread for it...
Okay, then I put my changes for the menu bar here in case anybody is interested in it. Thanks again for the hints and the help, adaliabooks and Maighstir!
// remove the purple bar above the menu bar, make the menu bar smaller and change the color to a brighter gray
addGlobalStyle('.menu::before { height: 37px; background-image: none !important; background-color: rgba(80, 80, 80, 1.0); }');
addGlobalStyle('.menu { height: 37px; box-shadow: none; }');
addGlobalStyle('.menu__container { padding-top: 0px; }');
addGlobalStyle('.menu__logo { line-height: 37px; padding-top: 0px; }');
addGlobalStyle('.menu-item { line-height: 37px; }');
addGlobalStyle('.menu-link__dropdown-icon { top: 14px; }');
addGlobalStyle('.menu-submenu { top: 37px; }');
Now I only would like to remove the darkening of the page when you access the menu and make the menu faster, but I'm afraid these are javascript functions and I have no clue how to search for them...
Edit: Found the solution in
ssokolow's user style.