Header Video

I’ve set a video in the header background. I want to reduce the height of the video without changing the widht.

I’m using this code
.wp-custom-header video {
display: block;
height: 550px;
max-width: 100%;
width: 100%; }

instead of the this default code below:

.wp-custom-header video {
display: block;
height: auto;
max-width: 100%;
width: 100%;}

Its getting the height reduced but also the width got reduced. I want the widht just 100% not reduced. please help me how to do that……

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