Remove position: relative from table elements

[barmac]

Describe the Bug

Also, the position: relative effect on i.a. table cells is undefined according to CSS 2.1 spec 🙈 https://www.w3.org/TR/CSS21/visuren.html#propdef-position
More on that here: https://stackoverflow.com/questions/4564638/using-position-relative-absolute-within-a-td

Originally posted by @barmac in #562 (comment)

As a result, at some point we might run into problems such as #540.

Expected Behavior

No more usage of properties which have undefined behavior in the spec.