A CodePen by Hakim El Hattab. Cloudy Spiral CSS animation - Started building a loading indicator but ended up with this... thing.

index.haml

.wrapper
  - (1..62).each do
    %i

%a{:href => "#black", :id => "black"}

script.js

// Set out to build a loading indicator 
// but ended up with this cloudy spiral 
// animation.
//
// - Hakim | @hakimel

style.scss

@import "compass";
$particles: 62; // has to match nodes in dom
$particleSize: 8px;
$radius: 80;
$lapDuration: 3s;

html, body {
  overflow: hidden;
  background: #3e6fa3;
}

.wrapper {
  position: absolute;
  top: 50%;
  left: 50%;
  z-index: 2;
  
  @include perspective(500px);
}

i {
  display: block;
  position: absolute;
  width: $particleSize;
  height: $particleSize;
  border-radius: $particleSize;
  opacity: 0;
  background: rgba(255,255,255,0.5);
  box-shadow: 0px 0px 10px rgba(255,255,255,1);

  animation-name: spin;
  animation-duration: $lapDuration;
  animation-iteration-count: infinite;
  animation-timing-function: ease-in-out;
}

@for $i from 1 through $particles {
  i:nth-child(#{$i}) {
    $angle: ( $i / $particles ) * 720;
    
    @include transform(
      rotate( #{$angle}deg )
      translate3d( #{$radius}px, 0, 0 )
    );

    animation-delay: $i * ($lapDuration / $particles);
  }
}

@keyframes spin {
  from {
    opacity: 0.0;
  }
  to {
    opacity: 0.6;
    transform: translate3d(-$particleSize/2, -$particleSize/2, 570px);
  }
}













// background color controls
#black {
  position: absolute;
  left: 10px;
  bottom: 10px;
  color: rgba(255,255,255,0.6);
  text-decoration: none;
  
  &:after { content: 'Black & white'; }
}

#black:target {
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
  background: #111;
  cursor: default;
  
  &:after { content: ''; }
}