The card text background has extra black color block when high contrast on

[Sheila111]

Describe the bug
The card text background has extra black color block when high contrast on

Steps to reproduce the behavior
1.Navigate to https://arcade.makecode.com/beta#
2.Settings----->High Contrast On
3.Clcik any card

Actual behavior
The card text background has extra black color block when high contrast on

The screenshot:

Additional context
1.OS: Windows(rs6)
2.arcade version: 1.3.31
3.Microsoft MakeCode version: 6.8.16

[riknoll]

This is intentional to make sure the text contrasts with the GIF background. We should probably hide the GIF though