Featured image of post Background Image Height 100 - In order to use different aspect ratios, divide the height of the original image by it's own width, and multiply by 100 to get the percentage value.

Background Image Height 100 - In order to use different aspect ratios, divide the height of the original image by it's own width, and multiply by 100 to get the percentage value.

300px 100px sets the width and height of the background image in percent of the parent element.