.resizer {
    width: 10px;
    height: 10px;
    background: blue;
    position: absolute;
    right: 0;
    bottom: 0;
    cursor: se-resize;
}

.resizer.ne {
    right: 0;
    top: 0;
    cursor: ne-resize;
}

.resizer.nw {
    left: 0;
    top: 0;
    cursor: nw-resize;
}

.resizer.sw {
    left: 0;
    bottom: 0;
    cursor: sw-resize;
}