It very much is not. One example: to prevent your flex container with an height from expanding to more than that height, you need to set the min-height to 0. Th

It very much is not. One example: to prevent your flex container with an height from expanding to more than that height, you need to set the min-height to 0. There is surely a good reason for that (I know there is, and I don't care why it is technically necessary), but this means that to use a very modern layout mechanism (flex) in a way that makes sense for the user (e.g. you want an app that is limited to the height of the page) you need to use another css rule that doesn't make apparent sense for a reason that you can understand only if you have a deep grasp on CSS in its entirety.