you can use pointer-events: none; to the element on top:
div {
width : 200px;
height : 200px;
float : left;
cursor : pointer;
border : 1px green solid;
}
div + div:hover { background: #a1a6c8; }
div:first-child {
pointer-events : none;
position : absolute;
top : 100px;
left : 100px;
border : 1px green solid;
background : #c1c6c8;
}
<div> on top of all: hover me </div>
<div>1</div>
<div>2</div>
<div>3</div>
<div>4</div>
<div>5</div>
<div>6</div>
as you can see, when you hover the element on the top the element behind is activated. For more info about this property: https://developer.mozilla.org/en/CSS/pointer-events