This is what we have currently to make YouTube embeds span the full post width:
.lazyYT-container {
height: 0 !important;
width: 100% !important;
padding-bottom: 56.25% !important;
}
IMO this is a big improvement and something like this should just be the default styling!
Not sure how to do the same for Vimeo (but YouTube accounts for probably like 99% of videos shared on our forum so not something we’ve worried about too much…)