align -items center centers the items vertically and this is happening correctly with your given code (try giving the main header a background ... ... <看更多>

I have a Flexbox course! https://www.flexboxsimplified.com/It seems like we mostly ever use align - items, but it's important to know how ... ... <看更多>

The cross-end margin edge of the flex item is placed flush with the cross-end edge of the line. center: The flex item's margin box is centered in the cross axis ... ... <看更多>

Bug: Setting min-height breaks align-items: center in ie11. You can set height explicitly, but in some situatio... ... <看更多>