Use nested selections for component-scoped styles

[benStre]

Currently, component selectors are added to each css block in a scoped stylesheet. The current regex replace strategy leads to invalid results for nested selectors. If nested selectors are supported in all browsers, a root component selector could be wrapped around the whole stylesheet:

uix-x {
  div {
    ...
  }
...
}

Alternatively, the @scope selector might be used.

[benStre]

Example: