Steps to Reproduce:

1. Generate a tainted reference warning in Beta
2. Click the Tainted References icon to get the popper
3. Hover over the frameless close button within the popper

Actual Results:

1. The bottom padding of the frameless close button (space between the button and the header divider line) is greater than the top padding.

2. The button icon size is too small.

Expected Results:

1. The button is aligned in the header. There's an equal amount of vertical spacing at the top (between the button and popper outline) and at the bottom (between the button and the header divider).

2. The size of the X icon should be 14px. It should be centred within a 32x32px button.

Please find specs in this Figma file.