Custom External Css for plotly.js

I added a range slider to the x-axis and on inspecting on my browser I found the un-dragged portion of the range slider to have a class name - “rangeslider-mask-min”. I tried to style it using its class name in an external CSS file but it did not work.

So basically, the whole problem is that for all the elements that are added by using plotly.js, I am not able to style them in an external CSS file.

Any solution for the same is appreciated. Thank You.