.iframe_player
    {
    width: 100%;
    height: 700px; 
    border-style: none;
    }

#prix_son
    {
    background-image: url("../image/sound/prix_du_son.png");
    background-size: contain;
    margin-bottom: 50px;
    }

.yt
    {
    width: 1280px;
    height: 720px;
    margin: auto;
    }

h2
    {
    }