CSS for admin-bar stops pages printing correctly

From what I can see, any front-facing page displaying the new admin-bar will print with a 28px margin-top on html, resulting in the last line of each page being obscured.

This happens even with all other styles disabled.

I tried making a function to insert a media=”print” style into the head, but it ends up ahead of the problem CSS ie:
html { margin-top: 28px !important; } and so gets overwritten.

Then I found a function which will successfully remove just the offending code:
add_theme_support( 'admin-bar', array( 'callback' => '__return_false') );

…and everything is still working fine! I can remove all the extra styles I made to fix my absolutely positioned elements.

I don’t understand why is this CSS being inserted at all. If it does have a purpose, why not add media=”screen”?

Has anybody else noticed that pages will not print properly when the admin-bar is present?