Wordpress - Admin bar and fixed header issue?

Try adding this to your CSS file:

body.admin-bar #branding-wrap{top: 28px;} 
body.admin-bar #wrapper{margin-top: 145px;}

the body.admin-bardeclaration at the front will make sure that these styles only get applied when the admin bar is visible.

in your css you could try something like: body.logged-in{margin-top:20px;} or if this doesnt work some other code using the .logged-in class