Change background upon hover

Hi there ! Thanks for the plugin !
I would like the fullscreen background to change when I hover a menu element.

I have tried the following code :

.menu-overlay .menu-item-76:hover {
background-image: url(‘https://dev.lesmichels.fr/wp-content/uploads/2019/07/About.jpg’)
}

But it only changes the background of the menu-item, not the whole background. Any idea on how to display it fullscreen ? Many thanks

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