Several attributes control how the button looks and which element it renders:

• tag renders a different HTML element in place of button
• class adds one or more CSS classes
• style sets a full CSS style string
• disabled set to yes disables the button

Reach for class first and keep the rules in a stylesheet. One class restyles every button that uses it, follows the colour palette and stays under the user's control. A hardcoded style overrides the theme and has to be repeated at every button, so use it only when no class can do the job.

style sets the whole style attribute and replaces anything a style.* attribute wrote before it, so do not mix the two.