1.11.4.2 - Justify content
Source: atoms/modifiers/_flex.scss, line 101
Flex utilities helps to justify flex content.
.is-justify-{breakpoint}-{alignment value}, breakpoint is optional.
alignment value:
- end
- start
- center
- between
- around
Examples:
Default styling 
                  Parent .is-d-flex.[modifier]
  Parent .is-d-flex.[modifier]
.is-justify-end
                  is-justify-end
Parent .is-d-flex.is-justify-end
  Parent .is-d-flex.is-justify-end
.is-justify-start
                  is-justify-start
Parent .is-d-flex.is-justify-start
  Parent .is-d-flex.is-justify-start
.is-justify-center
                  is-justify-center
Parent .is-d-flex.is-justify-center
  Parent .is-d-flex.is-justify-center
.is-justify-between
                  is-justify-between
Parent .is-d-flex.is-justify-between
  Parent .is-d-flex.is-justify-between
.is-justify-around
                  is-justify-around
Parent .is-d-flex.is-justify-around
  Parent .is-d-flex.is-justify-around
<div class="is-d-flex [modifier]">
  <div class="kss-box" style="flex: 0 0 60px">Parent .is-d-flex.[modifier]</div>
  <div class="kss-box" style="flex: 0 0 60px">Parent .is-d-flex.[modifier]</div>
</div>