The alt attribute for logos and buttons are done differently than the alt text used for other kinds of images. Google discusses the right way to do it. The best practices for logos and buttons are ...

Maybe it’s because I don’t like change, or maybe it’s because I hate it when software developers assume that everyone can figure out their cryptic icons, but I wasn’t a fan of Gmail’s recent makeover.

Buttons are a great way to add quick calls-to-action or links to important information. You can have buttons inline with the content or put them in a text block and place them in different regions.