Just took a look. Usually when you have an image with text like this, it’s better to add that image inside of the widget itself (inline) rather than have it as a background.
Background images that are responsive or designed to adjust with the browser sometimes won’t show certain parts of the image due to the size of the visitor’s browser. Browsers do their best to resize background images to fit the screen without stretching the image or losing too much quality.
Since the text in your image is wide, there isn’t much the browser can do to show all of it as a background while still showing the full height on a narrow browser…..unless it’s added as an inline image.
I would probably add a BLACK background image for the widget, and then add the image with the text inside the widget using the Custom HTML widget. <img src="LINK_TO_YOUR_IMAGE.png" alt="">
Let me know if that helps.