Different Tumblr theme creators use alternate coding methods to produce CSS themes. Because so many custom Tumblr themes exist, there are multiple ways to update a theme's CSS code.

Google's John Mueller reminded us that when it comes to your CSS background images, Google won't be indexing or ranking those images in image search. John Mueller said on Twitter "last I checked ...

Google's John Mueller said this morning in a webmaster hangout at the 20:55 mark that Google Image search does not index and rank images from CSS background code. He said if you want your images ...

Wybiral was able to do this by creating a grid of HTML DIVs that utilize CSS :hover selectors to request a new background image when your mouse moves over a box on the grid. As the image requests ...