Hi Alec:

This week I just practised changing the buttons in the control panel. Here are my suggestions:

• if you just want to change the style,  css/scss will work with more efficient performance .  Create a new css/scss file, use the class name on the button, and define your size、color、border、backgroud etc.
• if you want to add or change some element or other attributes(not style attrs),  you might need to overwrite the template;
• if you want to change the interaction behavior of the button,  you need to find the action method which bound on, and overwrite it in js or python file