.center{
    margin: 0 auto;
    max-height: 500px;
    max-width: 500px;
    text-align: center;
}
.portfolio-icon-holder{
    display: flex;
    flex-wrap: wrap;
    padding: 10px;
    margin: 10px;
}
.portfolio-icon{
    padding: 2px;
    width: 150px;
    height: 150px;
    margin: 30px 50px;
}