We currently have 2 values (center and middle) to achieve the same thing on align properties.
I am proposing to only keep center. Here's why: users could read the following example as "visually align the elementX between (the middle one) elementA and elementB".
<root>
<elementA>
<elementB>
<elementX>
</root>
root elementX { align: middle; }
This notion of ranking is absent from the center keyword hence its meaning is clearer.
Could you give us your opinion? If you don't have much to say just +1 or -1