How can I centre my images. Here is my code it seems its not working

Question

.project-container{

    width: 100%;

    display: grid;

    grid-template-columns: repeat(4, 1fr);

    grid-gap: 20px;
}



.project-card{

    position: relative;

    cursor: pointer;

    display: block;
}



.project-card img{

    width: 80%;

    height: 80%;

   display: center;
}