Deck: Background color for text selection

[bin101]

Describe the bug
The text background color variable doesn't apply in deck card editor in edit mode:

The text with the green circle is currently selected. And I do a mousover on the color-text-selection property inside the red rectangle but I don't get any value.

As workaround I set the color manually via the custom css plugin:

.CodeMirror .CodeMirror-selectedtext {
background-color: rgba(61, 174, 233, 0.50) !important;
}