#bord
{
background-color:red;
 margin: 0 auto;
}
 
#fond {
background: aqua;
background-size: cover;
border:4px solid black;
height:2475px;
min-width: 750px;
    max-width: 1000px;
    margin: 0 auto;
}

#debut {
text-align: center;
padding: 0;
margin: 0;
}

#img
{
text-align: center;
padding: -100;
margin: -1;
}

#def
{
width:600px;
height:245px;
  margin: 10px;
  border:2px solid black;
  display:inline-block;
  text-align:center;
  border-radius:10px;
  background-color: white;
}

#numerique
{
width:600px;
height:275px;
margin:0 10px; 
  border:2px solid black;
  display:inline-block;
  vertical-align:middle;
  text-align:center;
  border-radius:10px;
  background-color:white;
}

#num
{
width:650px;
height:450px;
margin:0 30px; 
  border:2px solid black;
  display:inline-block;
  vertical-align:middle;
  text-align:center;
  border-radius:10px;
  background-color:white;
}