Design updates as per #118288:
- Tweak text labels (colors, drop shadows)
- Strip border colors, inset outlines
- Muted strips are mostly gray, and their thumbnails are faded
- Overlapping strips are not semitransparent anymore
- Locked stripes only in content area
- Missing data blocks
- Updates to meta strips w/ missing data blocks
Pull Request: https://projects.blender.org/blender/blender/pulls/118581
c64050ecd2
