.grid-item:nth-child(2),
.grid-item:nth-child(3) {
    border: 1px solid #ccc;
    padding: 10px;
    overflow: hidden;
    position: relative;
}

.grid-item-wrapper {
    display: flex;
    flex-grow: 1;
}

.grid-item {
    border: 1px solid #ccc;
    padding: 10px;
    overflow: hidden;
    position: relative;
}

.resizer {
     width: 10px;
    cursor: ew-resize;
    background-color: rgba(0, 0, 0, 0.1); 
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
}