<style type="text/css">
	.caja {
	width: 80%;
    margin-left: auto;
    margin-right: auto;
    font-family: Arial;
    padding: 0.5em;
    position: center;
	}
		.caja header {
			width: 60%;		
			font-family: 'Roboto', sans-serif;
		    text-align: center;
		    padding: 20px;
		    font-size: 2em;
		    color: white;
		    margin: 0 0 25px; 
		    border-radius: 0px 23px 0px 23px;
		    -moz-border-radius: 0px 23px 0px 23px;
		    -webkit-border-radius: 0px 23px 0px 23px;
		    border: 2px solid #0944b8;
		    background: linear-gradient(#889ccf, grey);
		}
		
		.caja .calculadora {

			width: 12%;
    		margin: 0px 0px 25px; 
		    border-radius: 0px 23px 0px 23px;
		    -moz-border-radius: 0px 23px 0px 23px;
		    -webkit-border-radius: 0px 23px 0px 23px;
    		font-family: Arial;
    		padding: 3.5em;
    		border: 2px solid #0944b8;
    		position: relative;
    		left: 20%;
		}
	</style>