Hypothesis: This, together with Core modules (#EZP-24144) are the missing prices needed to be able to start to provide standard/base designs so that development cost/complexity of building web applications on top of eZ Platform comes down to/below what was the case in eZ Publish Legacy.

Earlier referred to as "Theming", this Epic is about adding a missing feature we had in 4.x: design system. The design system allows people to define different designs and extend one design inside another, both in terms of templates and design assets.

There is an existing bundle for this which we can almost use as is, but will need some integration work: https://github.com/liip/LiipThemeBundle
And as pointed out in Story attached to this, it will need to get cache support so it does not make the applications lower then it is.

Note: The makers of LiipThemeBundle has expressed that they are not using it, hence the inactivity, and think a future versions of a "Theme/Design feature" should be built on top of "Puli" instead