WordPress' built-in editor has an HTML mode that lets you override the background color of a post by changing its CSS (Cascading Style Sheet) background-color attribute to the color of your choice.

Using custom CSS, you can add a colored background to your posts without editing your posts in other ways and without changing the background of the rest of your blog's body.

Papa's Perspective 5-Minute Tour of CSS3 Background Gradients Major browsers support CSS3 gradients (including Internet Explorer 10), but with different rendering engines, it's still good to have ...