Add Colored Background Behind Inline Image Block

Site URL: http://www.blaynegoldwasser.com

Hello,

I am trying to add a colored background to sit behind my image.  I am just using an inline image block and want it to look more dynamic.  I've tried a few different codes but nothing seems to be working.

I want it to look something like this but instead of just half of the image, I want the background color to go all the way around the image block so the image is centered.

It is for this section of my website under "Technical Design"

Thanks!

Add to Design > Custom CSS

/* Techincal Design */
div#page-section-609c5dc1e110de06f4e1c979 .image-block-wrapper {
    overflow: visible !important;
}
div#page-section-609c5dc1e110de06f4e1c979 .image-block-wrapper:before {
    content: "";
    background: green;
    display: block;
    position: absolute;
    top: -20px;
    left: -20px;
    width: 50%;
    bottom: -20px;
    z-index: 999;
}

Sorry for the late reply.  I ended up changing my layout but I will definitely use this in the future.  Thank you for the tip!