body {
	background-color: lightskyblue;
	margin: auto 20%;
}

img {
	border: solid 2px blue;
	border-radius: 10px;
}

#caja header h1 {color: grey;}
#caja .cabecera h1 {color: blue;}
div nav h1 {color: red;}
nav > h1 {color: yellow;}