div {
  margin: 20px;
  display: inline-block;
}

#square {
  width: 50px;
  height: 50px;
  background: darkgreen;
}

#rectangle {
  width: 100px;
  height: 50px;
  background: darkgreen;
}

#diamond {
  width: 50px;
  height: 50px;
  background: darkgreen;
  transform: rotate(45deg);
}

#circle {
  width: 50px;
  height: 50px;
  background: darkgreen;
  border-radius: 50%;
}

#oval {
  width: 100px;
  height: 50px;
  background: darkgreen;
  border-radius: 50%;
}

#triangle-up {
  width: 0px;
  height: 0px;
  border-left: 25px solid transparent;
  border-right: 25px solid transparent;
  border-bottom: 50px solid darkgreen;
}

#triangle-right {
  width: 0px;
  height: 0px;
  border-top: 25px solid transparent;
  border-bottom: 25px solid transparent;
  border-left: 50px solid darkgreen;
}

#trapezoid {
  width: 60px;
  height: 0px;
  border-left: 20px solid transparent;
  border-right: 20px solid transparent;
  border-bottom: 50px solid darkgreen;
}