This is a quick 6-minute tutorial from my old Pro Web Design Course. You can’t buy the course any more (I’m replacing it with a new, better one), but I’m going to post some of the videos that are still helpful.
New CSS3 properties, including gradients, can replace a lot of instances where web designers would once have used an image file.
These new options can make our websites, themes, and apps a lot faster to load, by reducing the number of assets downloaded, and also more flexible, letting us change properties from a central CSS file instead of multiple images.
Note, because this is quite an old video, the version of Photoshop is CS1 (Windows). But the principles and approach will be the same for later versions of Photoshop.