*{margin:0px;}
.fondo {background-color: bisque;}
.caja1 {background-color: yellow; margin: 20px; border-color: black; border-style: solid; border-width: 3px; width: 7em; padding: 3px;}
.caja2 {background-color: rgb(0, 217, 255); margin: 20px; border-color: black; border-style: solid; border-width: 3px; width: 70em; padding: 3px;}
.caja3 {background-color: yellow; margin: 20px; border-color: black; border-style: solid; border-width: 3px; width: 7em; padding: 3px;}
.grande {font-size: larger;}
.rojo {color: red}