Hi Sherri,
Hope all is well.
There may be a couple of ways to resolve the issue at hand depending on how comfortable you feel with editing the image or using the custom less/css text area within the Authoring Tool.
1) Create the image at the size of the asset. The asset attached above is 8002px by 1669px which is quite a lot wider than the default Adapt max width (1440px). If the asset of the diamond and rectangle were roughly the actual size of the image (~160px wide by ~80px high) then you could use the inbuilt backgroundSize property to size it appropriately.
2) Add a custom class to the articles that you wish to apply the image to and add something similar to the following to the custom css/less text area in project settings:
.custom-class { background-size: 75%; }
(Replace 'custom-class' with the name of the class that you use)