.hero-one {
    position: relative;
    background-image: url('/media/coding.jpg');
    background-repeat: no-repeat;
    background-position: center;
    height: 500px;
    width: 100%;
    z-index: -1;
}

.hero-two {
    position: relative;
    background-image: url('/media/train.jpg');
    background-repeat: no-repeat;
    background-position: center;
    height: 500px;
    width: 100%;
    z-index: -1;
}

.underground-map {
    width: 90%;
    height: 500px;
    overflow: auto;
}

.bg-header {
    position: absolute;
    top: 0px;
}

.logo:hover {
    color: lightgrey !important;
}

.title {
    position: relative;
    top: 40%;
    margin-left: 10%;
    margin-right: 10%;
}

.overlay {
    position: absolute;
    background-color: rgba(0, 0, 0, 0.419);
    z-index: -2;
    width: 100%;
    height: 100%;
    overflow: hidden;
    top: 0px;
}

.article {
    text-align: justify;
}

.tree img, .binary-tree img {
    max-width: 300px;
}

section {
    padding: 0px !important; 
    margin: 0px !important;
}

.border-brown {
    border-left: 5px solid brown;
}



/* media screen repoonsive design */
@media screen and (max-width: 992px){
    .article {
        width: 80% !important;
        padding: 5px !important;
        font-size: 15px;
    }    
    
} 

@media screen and (max-width: 768px){
    .article {
        width: 90% !important;
        padding: 5px !important;
        font-size: 15px;
    }    
    
} 

@media screen and (max-width: 576px){
    .article {
        width: 100% !important;
    }

    .hero {
        margin: 0px !important;
        height: 250px;
    }

    .tree img, .binary-tree img {
        max-width: 250px;
    }

    .station-path .form-select {
        width: 75% !important;
    }
}