Use justify-content: flex-end and to have vertical scrollbar

I just had to face this issue myself and, after concluding it is a bug, I came up with a workaround.

In summary, don’t use justify-content: flex-end but rather put a margin-top: auto on the first child. Unlike flex-end this doesn’t break the scrollbar functionality, and it bottom-aligns the contents when they’re not overflowing the container.

Example based on @SrdjanDejanovic’s fiddle is at https://jsfiddle.net/peter9477/4t5r0t5b/

In case the example isn’t available, here’s the relevant CSS:

#container {
    overflow-y: auto;
    display: flex;
    flex-flow: column nowrap;
    /* justify-content: flex-end; DO NOT USE: breaks scrolling */
}
#container > :first-child {
    margin-top: auto !important;
    /* use !important to prevent breakage from child margin settings */
}

An alternative workaround that I believe I’ve also used is to add an extra container for the scrollbar. Use the flex-end on the inner container and have the outer container handle the scrolling. I generally dislike workarounds that require adding dummy elements though, so I prefer my CSS-only solution above.