I have the burger menu by default in my website (not only in mobile). I want to know how to change the backgroud color of sub-items and the line-height. I attach a screenshot: .
you can change the colors in Customizer > Colors > Off Canvas Panel
The menu item height can be adjusted in Customizer > Layout > Off Canvas Panel. If you want to change the sub-menu item independently you can use this CSS:
.slideout-navigation.main-navigation .main-nav ul ul li a {
line-height: 24px;
}