html {
  background-color: purple;
}

body {
  background-color: lightgoldenrodyellow;
}

table {
  margin: auto;
  background-color: lightgray;
  border-spacing: 16px;
}

td {
  width: 404px;
  height: 404px;
  text-align: center;
  vertical-align: middle;
  font-size: 2em;
  color: cornflowerblue;
}

#R1C1 {
  background-color: #ffff00;  
  background-image: url("radiation-128.png");
  background-repeat: no-repeat;
  background-position: top left;
}

#R1C2 {
  background-color: #ff7f00;
  background-image: url("biohazard-128.png");
  background-repeat: no-repeat;
  background-position: top center;
  }

#R1C3 {
  background-color: #ffffff;
  background-image: url("yin-yang-128.png");
  background-repeat: no-repeat;
  background-position: top right;
}

#R2C1 {
  background-color: #ff7f00;
  background-image: url("biohazard-128.png");
  background-repeat: no-repeat;
  background-position: center left;
}

#R2C2 {
  background-color: #ffffff;
  background-image: url("yin-yang-128.png");
  background-repeat: no-repeat;
  background-position: center center;
}

#R2C3 {
  background-color: #ffff00;
  background-image: url("radiation-128.png");
  background-repeat: no-repeat;
  background-position: center right;
}

#R3C1 {
  background-color: #ffffff;
  background-image: url("yin-yang-128.png");
  background-repeat: no-repeat;
  background-position: left bottom;
}

#R3C2 {
  background-color: #ffff00;
  background-image: url("radiation-128.png");
  background-repeat: no-repeat;
  background-position: center bottom;
}

#R3C3 {
  background-color: #ff7f00;
  background-image: url("biohazard-128.png");
  background-repeat: no-repeat;
  background-position: bottom right;
}