Docked view background not taking colour specified in stylesheet

I have specified the background colour in stylesheet as shown below. The variable is specified in a custom .css file. I have imported into light and dark theme. in the designer the colour is showing up correctly.

.ia_container--root{
	background-color: var(--GU_background);
}

When I am testing my application, I can see that the docked views are using default colour instead. After drilling down, I can see the desired colour show up when I change background colour from props of the view used as docked. I have inspected the object. It seems to show up on class="flex-container responsive container ia_container--primary view". But when I specified the custom colour in stylesheet, nothing seems to happen.

How are the background colour handled for docked views when using stylesheet?

I have attempted to use class for flex container, breakpoint container, .ia_container--secondary; nothing seems to work.

.docked-view{
	background-color: var(--GU_background);
}

resolved it.