a:hover {
  cursor: url("data:image/svg+xml;utf8,\
<svg xmlns='http://www.w3.org/2000/svg' width='100' height='100'>\
<circle cx='50' cy='50' r='25' fill='rgba(0,0,0,0.5)'/></svg>") 50 50, auto;
}

a:hover img {
  cursor: url("data:image/svg+xml;utf8,\
<svg xmlns='http://www.w3.org/2000/svg' width='100' height='100'>\
<circle cx='50' cy='50' r='25' fill='rgba(0,0,0,0.5)'/></svg>") 50 50, auto;
}