.parent {
width:300px;
height:300px;
background:#eee;
}
.child {
width:50px;
height:50px;
background:#fff;
}
.parent:hover .child{
background:#000
}
const Child = styled.div`
width:50px;
height:50px;
background:#fff;
`
const Parent = styled.div`
width:300px;
height:300px;
background:#eee;
&:hover ${Child}{
background:#000;
}
`;