Ineffective color contrast on radio buttons in the Sound Effect editor

Describe the bug

Building pxt and pxt-microbit on master, the Makecode Sound Effect editor waveform radio buttons do not contrast sufficiently to show which is selected (see screenshots below). Raising in pxt because this appears to be where the theme color is defined for this particular element.

To Reproduce

1. Create a Makecode project
2. Add a sound effect block
3. Click on the sound effect block to open the editor
4. Choose from the different waveform options

Expected behavior

I would expect it to be more obvious which of the waveform buttons is currently selected. This is a problem for visual accessibility. Previous versions, including the one at https://makecode.microbit.org, have had a clearer distinction between the selected and unselected buttons.

Screenshots

This is how it appears in master currently (this issue):

And this is how it used to appear (better contrast):

• OS: Mac OS
• Browser: chrome
• Version: 136.0.7103.48

Reproduce the issue in a MakeCode project by opening a sound effect block and selecting the waveform radio buttons. Inspect the Sound Effect editor's theme styling and compare selected versus unselected states with the screenshots; done when the selected waveform is clearly distinguishable and the contrast issue is resolved.