https://*.com/questions/38369015/customuzing-qtabwidget-with-style-sheets

QTabWidget::pane {
  border: 1px solid lightgray;
  top:-1px; 
  background: rgb(245, 245, 245);; 
} 

QTabBar::tab {
  background: rgb(230, 230, 230); 
  border: 1px solid lightgray; 
  padding: 15px;
} 

QTabBar::tab:selected { 
  background: rgb(245, 245, 245); 
  margin-bottom: -1px; 
}