Change DateTimeInput css style in theme folder


How can I change the background of datetimeinput popup below in my own theme's folder ?

I've changed background in mytheme/common/date-range-picker.css.
A part of the background still black. In which file I can change it ?

I'm interested in a document which describe how I can change all components property with CSS.


CSS doesn't change component properties. CSS applies to the visual appearance of components on the browser side, without any actual changes to the objects. You change object classes and/or direct styles to change what parts of your CSS apply to the given object, not the other direction.

CSS itself is a web standard from W3C and browser makers.

Press ctrl+shift+i in your browser to open the dev tools.
With it you can inspect elements on the page to find their classes and ids.
Then use those classes and ids to target whatever you want to change with css.



edit: yes, I know, dark theme bad