@media only screen and (max-width: 640px) {
    .navbar-brand > img{
        width: 180px;
        margin-left: 15px;
    }
    .navbar-toggle{
        margin: 15.5px;
    }
    .main_h{
        font-size: 36px;
        line-height: 50px;
    }
    .main_p{
        padding: 10px !important;
    }
    #ser_box{
        margin: 0 25px;
        height: auto;
        min-height: auto;
        margin-top: 40px;
    }
    #contact_box{
        height: auto;
        min-height: auto;
    }
}