The support article you quote is six years old and was for Pega 7.2.1 . It does not list a defect, but an enhancement request FDBK-18322 which was rejected because the issue could not be replicated and the scenario lacked information.
For the latest details please see other forum questions such as:
Q: How would we provide the styles such as a dynamic layout style?
A: yes - use non-auto-generated section - limit HTML and CSS descriptor to basic support like a table for example
Q: Could you provide an example of how we would pull it from the skin?
A: no - likely only the invalid/unsupported css selector is skipped but skip one selector can dramatically affect how the page looks like (especially if you are using a grid layout)
Did you look at the existing documentation for your version first?