<meta charset="utf-8">
<canvas width="600" height="400"></canvas>
<script>
var pantalla = document.querySelector("canvas");
var pincel= pantalla.getContext("2d");
pincel.fillStyle="darkgreen"
pincel.fillRect(0,0,350,300);
pincel.fillStyle="black"
pincel.fillRect(50,60,90,90);
pincel.fillStyle="black"
pincel.fillRect(210,60,90,90);
pincel.fillStyle="black"
pincel.fillRect(140,150,70,100);
pincel.fillStyle="black"
pincel.fillRect(100,190,40,110);
pincel.fillStyle="black"
pincel.fillRect(210,190,40,110);
</script>mi solución
