.s1_btn:nth-child(1){
    background-color: #333333;
}

#section_4{
    background-image: url(../../../sub/img/wrok/1.jpg);
    background-repeat: no-repeat;
    background-size: cover;
}

#in_s4{
    padding: 30px 0;
}

#section_3_1{
    margin: 30px 0;
}

.s4_txt{
    color: #ffffff;
}