Thank you for you reply
i did add in the overide.css
/* Here you can include your override CSS styles */
#gkMenuWrap {
background: transparent url('../images/leaves.png') top left no-repeat;
-webkit-box-shadow: 0 0 6px rgba(0, 0, 0, .26);
-moz-box-shadow: 0 0 6px rgba(0, 0, 0, .26);
box-shadow: 0 0 6px rgba(0, 0, 0, .26);
height: 70px;
left: 0;
position: fixed;
-webkit-transition: top .2s ease-out;
-moz-transition: top .2s ease-out;
-ms-transition: top .2s ease-out;
-o-transition: top .2s ease-out;
transition: top .2s ease-out;
top: -100px;
width: 100%;
z-index: 1001;
}
but nothing changes, in the source code of the site the
transparent url('../images/leaves.png') top left no-repeat;
does not appear