Easily add custom HTML outside the main container?

Question

My theme has set the max-width of the main container smaller than the screen size, and I'm searching for a way to override that in order to add a fullscreen video background.

Is there a relatively easy way to do this, without getting too technical?

Answer 1

I'd action this by adding an additional background video div to the code and positioning fixed. Just need to tweak the z-index to layer the main container and background video.

See demo: https://jsfiddle.net/t9mznyrq/