I believe that in order to better your knowledge base, it takes a lot of failing in order to succeed. I don't consider anything a failure as long as you get back up and you learn from your own mistakes.
Unknown

:host()

The :host() CSS pseudo-class function selects the shadow host of the shadow DOM containing the CSS it is used inside (so you can select a custom element from inside its shadow DOM) — but only if the selector given as the function's parameter matches the shadow host.
:host() css reference