Negative white space not working

edit those heading element you can find on styling tab at the bottom. : Spacing – and there bottom-padding
on default this is 10px – maybe it is enough vor you to set it to 0px ( negative paddings do not exist )

If those headings are of the same tag ( h2, h3 etc. ) you can use instead of two headings one with a <br> inside
Ignore the warning here – it will work – then you can manage the distance as line-height.

next: if these are two special headings following each other – they following will do have a margin-top value of 50px
so try:

#top .av-special-heading.el_after_av_heading {
  margin-top: 20px 
}