.intro {
  display: table;
  width: 100%;
  padding: 0;
  background: #e5e5e5 url(../img/old-lady-nurse.jpg) no-repeat center center;
  -webkit-background-size: cover;
  -moz-background-size: cover;
  background-size: cover;
  -o-background-size: cover;
}


.stimulus-image.top {
  grid-area: top;
  justify-self: start;
  align-self: top;
}

.stimulus-image.left {
  grid-area: left;
  justify-self: start;
  align-self: left;
}

.stimulus-image.right {
  grid-area: right;
  justify-self: end;
  align-self: center;
}

.stimulus-image.center {
  grid-area: center;
  justify-self: center;
  align-self: center;
}