#formulaire-responsive {
max-width:1400px ;
margin:0 auto;
width:100%;
}
.rang-form {
width: 100%;
}
.quart-colonne, .demi-colonne, .colonne {
float: left;
position: relative;
padding: 0.65rem;
width:100%;
-webkit-box-sizing: border-box;
-moz-box-sizing: border-box;
box-sizing: border-box
}
.clearfix:after {
content: "";
display: table;
clear: both;
} @media only screen and (min-width: 48em) { 
.demi-colonne {
width: 50%;
}
.quart-colonne {
width: 25%;
}