body {
  background-color: lightgray;
}

#cover {
    width: 100%;
    height: auto;
}

#cover > img {
  float: left;
  width: 50%;
  height: 50%;
}

a.overclick4 {
    float: left;
    position: absolute;
    top: 0; right: 0; bottom: 0; left: 0;
    width: 50%;
    opacity: 0;
    text-indent: -999em;
    }


a.overclick3 {
    float: left;
    position: absolute;
    top: 0%; right: 0; bottom: 0; left: 50%;
    width: 50%;
    opacity: 0;
    text-indent: -999em;
    }


a.overclick2 {
    float: left;
    position: absolute;
    top: 50%; right: 0; bottom: 0; left: 50%;
    width: 50%;
    opacity: 0;
    text-indent: -999em;
    }

a.overclick1 {
    float: left;
    position: absolute;
    top: 0; right: 0; bottom: 50%; left: 0;
    width: 50%;
    opacity: 0;
    text-indent: -999em;
    }
/*
a.overclick2:hover {
          background-color: #fff;
        opacity: 0.12;
        }
*/