How To Move New Tab Button Below Pinned Tabs?

[sapphired18]

I want to make it look alike Arc Browser, currently I am modifying the css, but I can't move it with display: flex; order: 0; for New tab button

based on arcwtf sidebery css

.TabsPanel {
   display: flex;
}

.TabsPanel .Tab {
   margin: 5px 0 0 0 ;
   order: 1;
}

/* NEW TAB BUTTON*/
.TabsPanel .new-tab-btns {
   padding: 0 10px;
   order: 0;
}