*{
    padding: 0;
    margin: 0;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
    
}
body{
    background-image: url(../portada.jpg) repeat-x;
    background: black;
    width: 100%;
    display: flex;
    justify-content: center;
}