Please, for your own good, preload your CSS images.

It’s becoming more popular to use the :hover pseudo-class to toggle a background-image in a <div> block to simulate various visual effects, but many developers are making the mistake of not preloading the :hover image. It looks unprofessional when a user hovers over an image and has to wait for a new background-image to download and display.

As you can see above, there is a small, awkward delay, which isn’t always so small, that occurs when a :hover background-image is not properly preloaded.

Read the rest of this entry »