Ugly corners

[BlackCube4]

I know this is a stupid complaint, but those corners really bother me...

[jensrossbach]

I think this is not a specific problem of this Lovelace card but more a generic problem of the browser's rendering engine. There is a workaround possible as described in this GitHub ghist. Although it is related to the Safari browser, I can confirm that it also works on Chromium-based browsers (tested on Edge and Fully Kiosk).

I say "workaround" because it doesn't solve the problem 100% but at least to a degree that you can hardly see the issue afterwards (especially on displays with high pixel density). Additionally the fix can be permanently applied to the slider-button-card using card-mod (apply to ha-card > div > div.slider).