Fix minor style issues across the toolkit

[daviddossett]

Describe the bug

Tracking an issue for myself to do the following:

• Ensure font stack mirrors VS Code on all platforms
• Double check dimensions on all components
• Double check interaction states on all components

[hawkticehurst]

Had another thought: might be nice to also do some light compare and contrast between our component styles and the CSS defined in the vscode/src/vs/base/browser/ui component folders.

[daviddossett]

Yep great idea!