#second_caption{
    width: auto;
    margin: -600px auto 100px auto;
}
#second_caption iframe{
    width: 90%;
    max-width: 820px;
}
.box_btn{
    display: block;
    margin: 60px auto 0 auto;
    padding: 0;
}
.box_btn a{
    display: block;
    margin: 0 auto;
    padding: 0;
    height: 50px;
    width: 260px;
    _background-color: red;
    _opacity: .5;
    position: relative;
}



@media screen and (max-width: 800px) {
    
    #second_caption{
        margin: -118% auto 10% auto;
    }
    
    .spotify-responsive-container{
        padding-bottom: 6vw;
        background-image: url(./sp_bgk.jpg);
        background-repeat: repeat;
        background-position: top center;
        background-size: 100%;
        margin: 0 -28px;
    }
    #second_caption iframe{
        width: 92%;
        height: 90vw;
        margin: 0 auto;
        text-align: center;
        display: block;
        max-width: 92%;
    }
    .box_btn{
        margin: 0 -28px;
        background-image: url(./sp_btn.jpg);
        background-repeat: no-repeat;
        background-position: top center;
        background-size: 100%;
        padding:0 0 10vw 0;
        position: relative;
    }
    .box_btn a{
        height: 15vw;
        width: 76%;

    }
}
@media screen and (max-width: 390px) {
    #second_caption{
        margin: -126% auto 10% auto;
    }
    #second_caption iframe{
        height: 92vw;
    }
}
@media screen and (max-width: 375px) {
    #second_caption iframe{
        height: 100vw;
    }
}