Videos at 16/9 ratio
Embedded videos, such as YouTube videos, should use the
yt-vid class on the
<iframe> tag to ensure they fit well with the web design grid and have visual balance. Without these classes, the videos may push the page out on smaller screen sizes or stretch the video. Eg
<iframe class="yt-vid" src="//www.youtube.com/embed/QMLlTH_2kR4" frameborder="0" allowfullscreen></iframe>
Please also note that videos should meet accessibility requirements as this is a legal requirement.