Windows 8 preloader (loading icon) using HTML5 and javascript without images

Question

I noticed a simple thing while looking at the screen of Windows 8 loading screen, there is a preloader (or loading icon) which is quite interesting, it has a bit of gravity/swin

Answer 1

Here is another take on the Modern UI ProgressRing animation in CSS3. It is based on the already mentioned Jan Rubio's solution with some tweaks (still needs tweaking, though).

Watch the live example or use the following code if the codepen is unavailable:

HTML

CSS (LESS, unprefixed)

body {background:#111}
@t:4000ms;
@d:40px;
@color:#ffffff;
.progress-ring {
  position: relative;
  padding-top: @d/5;
  width: @d;
  height: @d;
  margin: auto;

  .progress-ring__wrap {
    position: absolute;
      width: @d - 2;
      height: @d - 2;

    .progress-ring__circle {
      transform: rotate(225deg);
      animation-iteration-count: infinite;
      animation-name: orbit;
      animation-duration: @t;
      width: @d - 2;
      height: @d - 2;

      opacity: 0;

      &:after {
      content: '';
        position: absolute;
        width: @d/8;
        height: @d/8;
        border-radius: @d/8;
        box-shadow: 0px 0px 5% @color;
        background: @color; /* Pick a color */
      }
    }


    @r:-14deg;
    @m:30;
    &:nth-child(2) {
      transform:rotate(@r);
      .progress-ring__circle {  animation-delay: @t/@m; }
    }
    &:nth-child(3) {
      transform:rotate(@r*2);
      .progress-ring__circle {  animation-delay: @t/@m*2; }
    }
    &:nth-child(4) {
      transform:rotate(@r*3);
      .progress-ring__circle {  animation-delay: @t/@m*3; }
    }
    &:nth-child(5) {
      transform:rotate(@r*4);
      .progress-ring__circle {  animation-delay: @t/@m*4; }
    }
  }
}

@keyframes orbit { 
  0%   { transform:rotate(225deg); opacity: 1;
         animation-timing-function: ease-out; } 

  7%   { transform:rotate(345deg);
         animation-timing-function: linear; }

  35%   { transform:rotate(495deg);
          animation-timing-function: ease-in-out; }

  42%   { transform:rotate(690deg);
          animation-timing-function: linear; }

  70%   { transform:rotate(835deg); opacity: 1; 
         animation-timing-function: linear; }

  76% {opacity: 1;}

  77%   { transform:rotate(955deg);
         animation-timing-function: ease-in; }

  78% { transform:rotate(955deg); opacity: 0; }
  100% { transform:rotate(955deg); opacity: 0; } 
}