CSS(SASS)だけで作られた夜空に星が流れる パララックス 『Parallax Star background in CSS』

// n is number of stars required
@function multiple-box-shadow ($n) 
  $value: '#{random(2000)}px #{random(2000)}px #FFF'
  @for $i from 2 through $n
    $value: '#{$value} , #{random(2000)}px #{random(2000)}px #FFF'

  @return unquote($value)

$shadows-small:  multiple-box-shadow(700)
$shadows-medium: multiple-box-shadow(200)
$shadows-big:    multiple-box-shadow(100)

html
  height: 100%
  background: radial-gradient(ellipse at bottom, #1B2735 0%, #090A0F 100%)
  overflow: hidden

#stars
  width: 1px
  height: 1px
  background: transparent
  box-shadow: $shadows-small
  animation			: animStar 50s linear infinite

  &:after
    content: " "
    position: absolute
    top: 2000px
    width: 1px
    height: 1px
    background: transparent
    box-shadow: $shadows-small

#stars2
  width: 2px
  height: 2px
  background: transparent
  box-shadow: $shadows-medium
  animation			: animStar 100s linear infinite

  &:after
    content: " "
    position: absolute
    top: 2000px
    width: 2px
    height: 2px
    background: transparent
    box-shadow: $shadows-medium

#stars3
  width: 3px
  height: 3px
  background: transparent
  box-shadow: $shadows-big
  animation			: animStar 150s linear infinite

  &:after
    content: " "
    position: absolute
    top: 2000px
    width: 3px
    height: 3px
    background: transparent
    box-shadow: $shadows-big

#title
  position: absolute
  top: 50%
  left: 0
  right: 0

  color: #FFF
  text-align: center
  font-family: 'lato',sans-serif
  font-weight: 300
  font-size: 50px
  letter-spacing: 10px

  margin-top: -60px
  padding-left: 10px

  span
    background: -webkit-linear-gradient(white, #38495a)
    -webkit-background-clip: text
    -webkit-text-fill-color: transparent

@keyframes animStar
  from	
    transform: translateY(0px)
  to		
    transform: translateY(-2000px)