### Vertical-align colon/greater/less

# :> :< >: <:
# :>: :<:
# <:> >:< <:< >:>
# <::> <::< >::< >::>
# <:::> <:::< >:::< >:::>
# <::::> <::::< >::::< >::::>

lookup center {
    #574 :>= :<=
    ignore sub colon' [less greater] [equal hyphen];

    #1145 ::< ::> <:: >::
    ignore sub colon colon' [less greater];
    ignore sub [less greater]' colon colon;

    # middles & ends
    sub [less.center greater.center colon.center] colon' by colon.center;
    sub colon.center [less greater]' by [less.center greater.center];

    # starts
    sub [less greater]' colon by [less.center greater.center];
    sub colon' [less greater] by colon.center;
} center;