Revision slider steps are misplaced

[timobrembeck]

Describe the Bug

The version numbers of page and imprint revisions are placed a little bit off:

Steps to Reproduce

1. Go to the page editor
2. Create a few versions
3. Click on "Show versions"
4. See revision slider

Expected Behavior

The numbers should be placed exactly on the steps of the slider

Actual Behavior

The numbers are shifted a little bit

Additional Information

Make sure this works on recent versions of Firefox and Chrome. If the placement isn't 100% accurate on other/older browsers, that is acceptable.

Maybe it's a good idea to use a monospace font and disable font-size-adjust for the revision slider to make sure it looks the same on Firefox and Chrome.