I'm using Material UI Tabs in React to implement curved tabs (imagine like ones shown in Google Chrome). The structure must be such that the parent can give a bottom border which should stretch across the entire row making this bottom-border appear on tabs as well as on some other content on right. The selected (or active) tab, however, must remove the bottom border applied on it by its parent.
Expected Result:

Current Result:

The border from parent gets applied over the selected tab too, which is not what I want.
Here's the CodeSandbox link for my code.
Approach Taken:
I tried creating an ::after pseudo-element positioned absolute for selected tab with higher z-index. This pseudo-element creates a white-colored horizontal line and patches it over the bottom border applied by parent to overlap parent's border. However, I could not make it work. There were a couple of other CSS changes I applied; none seemed to move the parent's border. Any help to correct the existing approach I'm taking or suggesting a new approach to get the desired result is appreciated.
(Please note that I want to keep using Material UI Tabs as the base.)
On a side note, could anyone help why there's also some lag when selecting a tab?