Dead Simple Spin Loader

Loader.styl

.loader
    display flex
    justify-content center
    align-items center

    &.fullscreen
        min-height 100vh

    &:after
        content ""
        width 2.5em
        height 2.5em
        border 0.5em solid lightgray
        border-radius 50%
        border-top 0.5em solid black
        animation spin 1s linear infinite

@keyframes spin
  0%
    transform rotate(0deg)
  25%, 75%
    border-color lightgray
    border-width 0.75em
    transform rotate(180deg)
    border-color black
  50%
    border-width 1em
  100%
    transform rotate(360deg)