* { margin:0;
     padding:0;}

body { background-color: #919191;
}

header { background-color: #e50d69;}

aside { background-color: #00ff3b;float: right; width: 25%}

footer { background-color: #00ff3b;
clear: both; }

div#test { background-color: rgba(40, 74, 214, 0.45);
width: 100%; 
margin:auto;
}

main { background-color: #00ff3b;
}

h2 { background-color: #00ff3b;
clear: both; }

.uno { background-color: #a8a8a8;}

.dos { background-color: #f00;
    float: left;
    list-style: none;}

ul li {
    float: left;
    list-style: none; 
 }
div#imagen_principal { background-color: rgba(40, 74, 214, 0.45);
width: -150%; 
margin:auto;
}