Streaming live at 10am (PST)

Mix-blend-mode and isolation

Hi,
I try to create an “inverted” flashlight effect with an black circle. (later with mouse-movement)
Therefore the circle is set to mix-blend-mode:darken.
But the circle should not inherit the background and other elements. Only the text underneath.
I found the isolation: isolate css-value, but I can´t get it working.
The effect I would like to achieve:


Here is my site Read-Only: LINK
(how to share your site Read-Only link)