Website Menu & Mobile Menu

Hi,

I recently added an image to a menu button, using:

.menu-elephant-walk-experience {
background: url(http://millenniumelephantfoundation.com/wp-content/uploads/2016/04/5-gold-stars.png);
}

But this also changed the mobile version menu button which I did not want to change, how can I avoid this?

Many thanks for your time.