Why use a basic button when you can instead use a “picture” button? Earlier, you created a Submit button using a basic Windows-style button and then added an onclick event. You also changed the cursor to that of a pointer, which helped to make the button appear clickable. However, you could further enhance the button by replacing it with a picture and then, in conjunction with setting an onclick event you could also set a mouse event so that the picture image was swapped with a different image on hover over.
The following assumes you have your site open in SharePoint Designer and the site is based on a Team site which includes a Site Assets library.
1. Upload two button images (or any images you want to use as buttons) ...