Ejemplo 1. CSS
	*{
	margin:0;
	padiing:0;
}

body {
background: #f6f5f5;
font-family: Candara;
color: black;
text-align:center;
}
header {
	width: 100%;
	max-width: 100%;
	margin: 20px auto;
	color: black;
}
.mostrar {
	text-align:left;
  background-color:#F1F1F1;
  border:1px solid #00000;
  padding:10px;
  overflow:auto
  margin:7px;
  color:#0150c7;
  
}
footer {
	background: grey;
	color: white;
	clear:both;
	padding:10px 0px;
	}