Background video sizing responsiveness + mobile

[Port_of_Folio]

Couple of ways to achieve this. See link below. This is assuming that your video is 16:9 ratio.

Auto Resize Background Video While Maintaining 16:9 Ratio & Margins

If anyone is looking for an updated way to do this, you can add the aspect-ratio css property with custom code: <style> .video, .video video {aspect-ratio: 16 / 9; width:auto !important;} </style>