TryGhost/Ghost

/*

    BORDERS

    Base:
      b = border

    Modifiers:
      a = all
      t = top
      r = right
      b = bottom
      l = left
      n = none

   Media Query Extensions:
     -ns = not-small
     -m  = medium
     -l  = large

*/

  .ba { border-style: solid; border-width: 1px; }
  .bt { border-top-style: solid; border-top-width: 1px; }
  .br { border-right-style: solid; border-right-width: 1px; }
  .bb { border-bottom-style: solid; border-bottom-width: 1px; }
  .bl { border-left-style: solid; border-left-width: 1px; }
  .bn { border-style: none; border-width: 0; }
  .oln { outline: none; }


@media (--breakpoint-not-small) {
  .ba-ns { border-style: solid; border-width: 1px; }
  .bt-ns { border-top-style: solid; border-top-width: 1px; }
  .br-ns { border-right-style: solid; border-right-width: 1px; }
  .bb-ns { border-bottom-style: solid; border-bottom-width: 1px; }
  .bl-ns { border-left-style: solid; border-left-width: 1px; }
  .bn-ns { border-style: none; border-width: 0; }
  .oln-ns { outline: none; }
}

@media (--breakpoint-medium) {
  .ba-m { border-style: solid; border-width: 1px; }
  .bt-m { border-top-style: solid; border-top-width: 1px; }
  .br-m { border-right-style: solid; border-right-width: 1px; }
  .bb-m { border-bottom-style: solid; border-bottom-width: 1px; }
  .bl-m { border-left-style: solid; border-left-width: 1px; }
  .bn-m { border-style: none; border-width: 0; }
  .oln-m { outline: none; }
}

@media (--breakpoint-large) {
  .ba-l { border-style: solid; border-width: 1px; }
  .bt-l { border-top-style: solid; border-top-width: 1px; }
  .br-l { border-right-style: solid; border-right-width: 1px; }
  .bb-l { border-bottom-style: solid; border-bottom-width: 1px; }
  .bl-l { border-left-style: solid; border-left-width: 1px; }
  .bn-l { border-style: none; border-width: 0; }
  .oln-l { outline: none; }
}