<video id="background-video" autoplay loop muted>
    <source {{ with .Params.header_video }}src="{{ . }}"{{ end }} type="video/webm">
</video>

#background-video {
width: 100vw;
height: 100vh;
object-fit: cover;
position: fixed;
left: 0;
right: 0;
top: 0;
bottom: 0;
z-index: -1;
}