Promoted Links Colour

Hi

I would like to change the background/overlay colour on promoted links, either page by page or site wide if possible. From what I've found so far the grey text background colour can be changed by adding some code into a content editor web part on the page but when i have done this and click save the code is visible and nothing has changed.

Is there a mistake in the code below or another way to do this? thanks

<style type="text/css">
.ms-tileview-tile-content{
	background-color:navy! important;}</style>