In the compass-shell component, text selection color has not enough contrast compared to the background color when the editor is in focus, not sure whether this is intentional or a bug.

The text selection color is: #233 while the background color is: #112733 (gray.dark4)

I have tried to look where the selection color is defined but couldn't find within the compass repo (maybe in codemirror?).

Anyway, it seems that in compass-editor/json-editor.tsx there is a definition for the selection color, which provides a good contrast, but that is only active when the shell is not in focus, a possible fix would be to add this rule in getStylesForTheme:

'&.cm-focused .cm-selectionBackground': {
    background: editorPalette[theme].selectionBackgroundColor
}, 

Thanks.