Ability to style <details>/<summary> to be open (e.g. for print styles) #2084
Description
(Not quite sure which spec this would relate to specifically, sorry)
If a page uses <details>/<summary> expand/collapse blocks, there currently appears to be no way to open these via CSS. This poses problems for print styling: if I wanted to have these blocks appear open when printed, it seems that the only solution is to first run JS over the document and add the open attribute on the <details>.