@media screen and (max-width: 990px) {
    .hero-text {
        width: 100%;
    }

    #main-div {
        height: auto;
        overflow: hidden;
    }

    .about-title {
        font-size: 20px;
        margin-top: 4%;
    }
}

@media screen and (max-width: 770px) {

    .hero-text h1 {
        font-size: 35px;
        padding-top: 40%;
    }

    .hero-text p {
        font-size: 12px;
    }
}

@media screen and (max-width: 750px) {

    .hero-text h1 {
        font-size: 30px;
    }
}

@media screen and (max-width: 670px) {

    .hero-text h1 {
        font-size: 30px;
        padding-top: 20%;
    }  
}

@media screen and (max-width: 400px) {
    .hero-text {
        width: 80%;
    }

    .hero-text h1 {
        padding-top: 10%;
    }

    .hero-text p {
        width: 70%;
    }

}