This value tells browsers to make the image repeat across the page and down the page to produce a grid effect. Delete that statement if you don't want your GIF to create a tiled background.

How to Change a Background Dynamically in a Website. Using CSS and JavaScript, you can dynamically change the background on your website. You use the code to change the background each time a user ...

Ryan Boudreaux includes all the code snippets you'll need in this demo of how to create an image hover-preview effect using HTML, CSS, and JavaScript.

We need the original picture to be behind the overlay so we’re making it a background image using the CSS property ‘background’. The PNG overlay is then set as the new SRC for the IMG element.