gtk/testsuite/reftests/box-shadow-spec-inset.css

GtkButton {
  engine: none;
  border-radius: 0;
  background-image: none;
  border-image: none;
  border-style: none;
  background-color: rgba(0, 0, 0, 0);
  border-width: 0;
}

.row1, .row2, .row3 {
  /*border:5px solid blue;*/
  border-width: 5px;
  border-style: solid;
  border-color: blue;
  background-color:orange;
}

.column1 {
  /* border-radius: 20px */;
}

.column2 {
  border-radius: 0;
}

.row2 {
  box-shadow:
    rgba(0,0,0,1)
    15px 15px
    inset
}

.row3 {
  box-shadow:
    rgba(0,0,0,1)
    15px 15px 0
    10px /*spread*/
    inset
}

.reference-border {
  border-width: 5px;
  border-style: solid;
  border-color: blue;
}

.reference-background {
  background-color: orange;
}

.reference-shadow {
  background-color: rgba(0,0,0,1);
}

/*
.reference-padding-radius {
  border-radius: 15px
}

.reference-radii1 {
  border-radius: 15px 0 10px;
}

.reference-radii2 {
  border-radius: 5px 0 10px;
}
*/