var pantalla = document.querySelector("canvas");
var pincel = pantalla.getContext("2d");
pincel.fillStyle = 'darkgreen';
pincel.fillRect(200, 50, 350 ,300);
pincel.fillStyle = 'black';
pincel.fillRect(250, 100, 90, 90);
pincel.fillRect(410, 100, 90, 90);
pincel.fillRect(340, 190, 70, 100);
pincel.fillRect(300, 240, 40, 110);
pincel.fillRect(410, 240, 40, 110);