If you're trying to figure out which element you need to adjust on the Colors and Styles screen to change a particular gadget component, you can use the Inspect option that's available on all modern browsers.
To use this option, right click over the component you want to change and select the Inspect option.
In the window that appears, the selected component should appear highlighted and surrounded by HTML tags.
In most cases, the tag should correspond to the element you need to adjust on the Colors and Styles screen. If, for example, the component is surrounded by <H4> tags, then, to change the appearance of this element, you would adjust the H4 or Heading 4 element under Typography on the Colors and Styles screen.