After looking into the rendered html with IE8 and its developer tools (press F12 to get these, then CTRL-B to click an element in the page and have its tag selected in the developer tool), I discoverd an
a-element above my Menu:
Menuis my own
div, in it you see the
ct100_Menu1_2which is the actual menu, with 2
aelements around it)
After looking into this
#ct100_Menu1_SkipLinkI found a property
SkipLinkTexton the Menu control. If you set it to the empty string (
SkipLinkText=""), the strange empty space is gone!
Please be aware though, that these SkipLinks are meant for people who are using a screen reader. The text in it is read aloud and allows a visually impaired user to skip the menu and jump to the contents of the page by following this link. The fix I described here removes this so-called skiplink and thus makes your page less user-friendly for the visually impaired.