body{margin:0px; padding:0px; font-family:'Arial'; font-size:16px; background:rgba(0,0,0,0.15); color:#000}
.sombra{-webkit-box-shadow: 2px 2px 4px 0px rgba(50, 50, 50, 0.7);
-moz-box-shadow:    2px 2px 4px 0px rgba(50, 50, 50, 0.7);
box-shadow:         2px 2px 4px 0px rgba(50, 50, 50, 0.7);}
.centrar{position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%);}
input[type="text"], input[type="password"], input[type="email"], select{ width:80%; 
-webkit-border-radius: 5px;
-moz-border-radius: 5px;
border-radius: 5px;
border: solid 1px #CCC; margin:3px;
}
input[type="button"], input[type="submit"]{background:green; color:#fff; cursor:pointer; text-align:center; 
-webkit-border-radius: 5px;
-moz-border-radius: 5px;
border-radius: 5px;border: solid 1px #000; margin:3px; height:25px; padding:0px 15px 0px 15px;
}
input[type="button"], input[type="submit"]:hover{background:#999; color:#000;}

input:invalid {
border: 1px solid red;
}
/* Estilo por defecto */
input:valid {
border: 1px solid #000;
}
.full{width: 100%;}
.mitad{width: 50%;}
.small{width: 60px;}
.medio{width: 120px;}
.largo{width: 350px;}