Half of black "close" button for windows in workspace overview is on black background, hard to distinguish
As you know, we can close applications (windows) directly from the workspace overview (press Super key to show it). We mouse is over the window, an "X" button pops up in the upper right corner and it lets you to close that window. Unfortunately, current colour scheme makes hard to recognize "close" button, especially if it falls outside the wallpaper. To more more precise, this issue happens with "unlucky" colours combinations: in this case, dark background.
As you can see in this screenshot, it's hard to recognize the button of the Firefox window;
I suggest to colour/fill it red (it better identify the "definitive" action, if you click on it) or at least, make the border with red colour.
Using gnome-shell 40.0 on latest Arch Linux.
Steps to reproduce it (e.g.):
- open two instance of Gedit (in the same workspace)
- enter workspace overview (press Super key)
- move the mouse on the right window; and the "close" button will pop up
EDIT: added some information as requested below