Add Custom CSS To Specified Menu Item

Hello!

I’m trying to add a background image to a menu item in a sub menu for my site: https://rslspeakers.com/.

WordPress assigns each menu item with a unique id number. I’ve tried to add the background to it in CSS using this unique id number which I found in the source code.

I’ve been able to add it successfully in the elements panel in Chrome however.

The sub menu item is labeled “5.1 Product Showcase” under Products. Here is the CSS I’m trying to add to it (I’ve tried changing the CSS reference id & class):

li#menu-item-2153.menu-item-2153 {
	background: transparent url('https://rslspeakers.com/wp-content/uploads/Tiny-New-Icon.png') no-repeat right !important;
	background-size: 27px 27px !important;
}

Any information will be greatly appreciated.

Thanks,