<!DOCTYPE html>.flex-container {display: -webkit-flex;display: flex;-webkit-flex-direction: column;flex-direction: column;width: 400px;height: 250px;background-color: lightgrey;}.flex-item {background-color: cornflowerblue;width: 100px;height: 100px;margin: 10px;}class="flex-container"class="flex-item"flex item 1class="flex-item"flex item 2class="flex-item"flex item 3