body{
    background: black;
    margin: 0;padding: 0;
}
h1{
    font-size: 2vmax;
    color: bisque;
    border: 2px solid red;
    text-align: center;
    padding: 1vmax;
    margin: 1vmax 5vmax;
}
#Debut_tab{
    /* text-align: auto; */
    border: 1vmax solid blue;
    margin: 0.5vmax;
    display: block;
    width: 90%;
    height: 10%;
    margin-left: auto;
    margin-right: auto;
}
.cadre_image{
    text-align: center;
}
.thumb{
    text-align: center;
    width: 20%;
    height: auto;
    display: inline-block;
    padding: 0.5vmax;
}
.thumb:hover{
    width: 21%;
    border: 0.2vmax solid red;
}
.btn {
    text-align: center;
    width: 60vmin;
    height: 6vmin;
    font-size: 2vmax;
    padding: 0.5vmin 1vmin;
    margin: 1vmin auto;
    background:#007bff;
    color:#fff;
    text-decoration:none;
    border-radius:4px;
    display: block;
}
.btn:hover { background:#0056b3; }