.main_img {
    width: 50%;
    margin-left: 25%;
    margin-top: 5%;
    padding-bottom: 20px;
    background: #CCCCCC
}

.qs_title {
    font-size: 22px;
    line-height: 64px
}

.qs_title2 {
    font-size: 15px;
    line-height: 30px
}

.qs_title3 {
    font-size: 18px;
    line-height: 42px
}

.qs_title4 {
    font-size: 15px;
    line-height: 38px
}

@media only screen and (max-width: 750px) {
    .main_img {
        width: 80%;
        margin-left: 10%;
    }

    .qs_title {
        font-size: 18px;
        line-height: 48px
    }

    .qs_title2 {
        font-size: 10px;
        line-height: 20px
    }

    .qs_title3 {
        font-size: 14px;
        line-height: 32px
    }

    .qs_title4 {
        font-size: 12px;
        line-height: 24px
    }
}