Style fixes for mini resolver

Make the icon 48dp.
Update button style to be opaque for "Open" and outlined for the browser
button.
Fix button padding at the bottom.

Test: Visual inspection with UX. Tested in gesture/3-button + light/dark
      theme
Bug: 175433480
Change-Id: I9304ee6fed28a467fcc54630dab18aaf4f140986