h3{
margin-left: 20px;
}

ol > li {
  margin: .5em 0;
}

.body{
margin-left: 5px;
}

.header{
text-align: center;
margin-bottom: 100px;
}

.lectures{
color: black;
text-decoration: none;
}

.lectures:hover{
text-decoration: underline;
}

.seances{
float:left;
width:48%;
padding:1%;
}