CSS Problem: Setting Native Button' active styling

I am trying to create a navigation bar with 4 native buttons in a CSSlayout, my buttonstyleLayout needs to show a background image when each button is clicked and then stay active until another button is clicked.

This CSS only shows the background when pressed but the image does not stay there?

.v-csslayout-buttonlayoutStyle .v-nativebutton:active,
.v-csslayout-.buttonlayoutStyle .v-nativebutton.v-pressed
	   background: transparent url(img/buttonBack.png) no-repeat;

How can i show my background back button after each button click in the navigation bar.