CSS is currently centralized, should be componentized?

[danielweck]

https://github.com/readium/readium-desktop/tree/develop/src/renderer/assets/styles

=> all in one folder, but should be tied to specific JSX component?

[danielweck]

Related: #409

[danielweck]

A concrete problematic situation related to this issue:
#681 (comment)

[danielweck]

Also note that some SVG icons contain non-parameterized inline CSS definitions:
https://github.com/readium/readium-desktop/tree/develop/src/renderer/assets/icons

For example:

<style type="text/css">
	.st0{fill:#C1C1C1;}
</style>

This could cause problems when implementing support for OS high-contrast / dark mode.
See #577

The solution we will likely implement is CSS "variables" (custom properties), just like ReadiumCSS, at which point the SVG icons might need tweaking too.