.feed_post {
    width:100%;
    height:100%;
    background-size:cover;
    background-position: 0;
}

.feed {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(32%, 1fr));
    grid-auto-rows: 1fr;
    grid-gap: 4px;
}
  
.feed::before {
    content: '';
    width: 0;
    padding-bottom: 100%;
    grid-row: 1 / 1;
    grid-column: 1 / 1;
}
  
.feed > *:first-child {
    grid-row: 1 / 1;
    grid-column: 1 / 1;
}