Why don’t HTML edits stick?

I’m trying to change the background color of a paragraph like this:


<p style="background-color:#FFFF00">This block of text has a yellow background


I am adding the tag information in the HTML editor.

But after I click the “Update” button in on the HTML editor, then “Save” the post, the HTML edits I’ve made are gone!

Am I missing something? What is the best way to change font/background color in posts?