CSS Flex

For Containers:

justify-content: how the flex items will be aligned along main axis
options: flex-start | flex-end | center | space-between | space-around | space-evenly

align-items: how the flex items will be aligned along cross axis
options: flex-start | flex-end | center | baseline | stretch

align-content: which only applies when there is more one row of flex items,
in that case, align-content controls how the rows aligned along cross axis
if there are some empty space.
options: flex-start | flex-end | center | space-between | space-around | stretch