1 px border behaviour

by agib

HTML

<div>
    
</div>

CSS

div {
    margin: 100px;
    height: 100px;
    width: 100px;
    border-top: 1px solid Red;
    border-right: 1px solid Yellow;
    border-bottom: 1px solid Blue;
    border-left: 1px solid Green;
}