Sticky top bar

Hi,
Our sites use a top module bar which sticks in the viewport even when the reader scrolls down. It is similar to what can be seen on tiki.org. Our site uses a custom theme with a hack to implement this sticky bar. We have issues in some places with the sticky bar hiding content.

First, how does tiki.org implement its sticky bar?

I see that when one clicks a link in the floating table of contents on https://dev.tiki.org/Overview the title of the clicked section is fully visible. I can see CSS related to that in the main document:
/* Prevent target anchors from being covered by fixed top navbar */
h1:target:before,
h2:target:before,
h3:target:before,
h4:target:before,
h5:target:before {
  content:"";
  display:block;
  height:72px; /* fixed header height*/
  margin:-72px 0 0; /* negative fixed header height */
}

Is this code specific to dev.tiki.org?