A 1px window border below tab bar

This is maybe a bug of window border of Microsoft Edge Insider and Chromium.

Under Windows 10, if you unselect "Window Border and Title Bar Color" in "Settings - Personalization - Color", a 1px colored window border will appear on the top of the blank above the tab bar of Microsoft Edge Insider. It's so ugly.

screenshot like this : https://i.loli.net/2019/06/16/5d05c8572209587763.png