.calculadora {
	text-align: center;
    width: 700px;
    margin: auto;
    border: 3px solid black;
    padding: 10px;
    background-color: lightgrey;
}

 .pantalla { 
 	border-width:2px; 
 	border-color:#cccccc; 
 	border-style:solid; 
 	font-size:42px; 
 	padding:5px; 
 	text-align:right; 
 	box-shadow:inset -3px 0px 30px 0px rgba(130,130,130,.75); 
 	font-family:monospace;  
 } 
	 
.pantalla:focus { outline:none; } 

.normal {
	float: left;
	border-width:1px; 
 	border-color:#000000; 
 	border-style:solid; 
 	padding:5px; 
 	text-align:center;
}

.clear {clear:both;}

h2 {
	font-size: 16px;
	font-weight: bold;
	font-family: Verdana;
}