body
{
margin:0;
text-align: center;
background-color: white;
font-family: helvetica, arial, sans-serif;
}

.conteneur
{
display: flex;
justify-content: center;
align-items: center;
}

.central
{
position: absolute;
left: 50%;
top: 50%;
transform: translate(-50%,-50%);
}