appeared working-line on top after jump from bottom

[Uwe Speckels]

I created an alphabetical list with links on every letter. After clicking on the letter the list will be forwarded to the letter description.  The alphabetical letter list is fix on top - example-1.

If I click on B then the jump follows to the letter B. At the end of the letter box you can click on -top-. So you can start with a new letter in the glossary - example-2.

After click on -top- a working line appears in the front and behind this there is the alphabetical list - example-3.

Question: how can I delete this added line so I can see the list line?

You can see the programmed line in - example-4

Thanks in advance.