it WORKS! 😀 i missed this percentage width yesterday. haha.
i put the width on theme default width location, not on custom css. i put 33.33% because i want 3 posts each row (6 total)
for smaller screen, using percentage causing the related posts too small, so i change it to 50% for screen under 520px using @media screen and (max-width: 520px). although i know 520px isn't the correct @media screen size for mobile.
i can't make the rpp box (rpp_item) full width, i put frame on the rpp_wrapper, in fact i want it to be more right, inline with the paragraph https://i.imgur.com/KoLei0x.jpg
any idea to push the rpp_item a little bit right for left item and a little bit left for right item? can't use margin because the margin between box will be too big, and can't use margin-left or margin-right because on smaller screen will change to 50%