Changing CSS variables via JS in Polymer

Question

In my Polymer project, I have a toolbar with a color I want to change using JavaScript. Since Polymer uses the CSS variable — paper-toolbar-background internally for styling

Answer 1

Basically,

1. Grab the element
2. Use the customStyle property to alter --paper-toolbar-background
3. Run element.updateStyles()

Please see the docs. [Edit] If you need an example, I've one here.