.duct_group img:hover{
    box-shadow: 0 20px 20px rgba(0,0,0,0.5);
    text-decoration: none;
    cursor: pointer;
    border: 1.5px solid blue;
    border-radius: 0.5em;
}

.duct_group{
    float: left;
    border: 1px solid gray;
    margin: 0.2em;
    border-radius: 0.5em;
}
.duct_group img{
    width: 5em;
    height: 5em;
    border-radius: 0.5em;
}

.nav-item{
    color: #007BFE;
    cursor: pointer;
}