Pure CSS Fireworks

firework.html

<div class="pyro fadeOut">
  <div class="before"></div>
  <div class="after"></div>
</div>

firework.scss

$particles: 50;
$width: 500;
$height: 500;
// Create the explosion...
$box-shadow: ();
$box-shadow2: ();
@for $i from 0 through $particles {
  $box-shadow: $box-shadow, random($width)-$width / 2 + px random($height)-$height / 1.2 + px hsl(random(360), 100, 50);
  $box-shadow2: $box-shadow2, 0 0 #fff
}

@mixin keyframes ($animationName) {
  @-webkit-keyframes #{$animationName} {
    @content;
  }
  @-moz-keyframes #{$animationName} {
    @content;
  }
  @-o-keyframes #{$animationName} {
    @content;
  }
  @-ms-keyframes #{$animationName} {
    @content;
  }
  @keyframes #{$animationName} {
    @content;
  }
}

@mixin animation-delay ($settings) {
  -moz-animation-delay: $settings;
  -webkit-animation-delay: $settings;
  -o-animation-delay: $settings;
  -ms-animation-delay: $settings;
  animation-delay: $settings;
}

@mixin animation-duration ($settings) {
  -moz-animation-duration: $settings;
  -webkit-animation-duration: $settings;
  -o-animation-duration: $settings;
  -ms-animation-duration: $settings;
  animation-duration: $settings;
}

@mixin animation ($settings) {
  -moz-animation: $settings;
  -webkit-animation: $settings;
  -o-animation: $settings;
  -ms-animation: $settings;
  animation: $settings;
}

@mixin transform ($settings) {
  transform: $settings;
  -moz-transform: $settings;
  -webkit-transform: $settings;
  -o-transform: $settings;
  -ms-transform: $settings;
}

body {
  margin: 0;
  padding: 0;
  background: #000;
  overflow: hidden;
}

.pyro>.before,
.pyro>.after {
  position: absolute;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  box-shadow: $box-shadow2;
  @include animation((1s bang ease-out infinite backwards, 1s gravity ease-in infinite backwards, 5s position linear infinite backwards));
}

.pyro>.after {
  @include animation-delay((1.25s, 1.25s, 1.25s));
  @include animation-duration((1.25s, 1.25s, 6.25s));
}

@include keyframes(bang) {
  to {
    box-shadow: $box-shadow;
  }
}

@include keyframes(gravity) {
  to {
    @include transform(translateY(200px));
    opacity: 0;
  }
}

@include keyframes(position) {
  0%,
  19.9% {
    margin-top: 10%;
    margin-left: 40%;
  }
  20%,
  39.9% {
    margin-top: 40%;
    margin-left: 30%;
  }
  40%,
  59.9% {
    margin-top: 20%;
    margin-left: 70%
  }
  60%,
  79.9% {
    margin-top: 30%;
    margin-left: 20%;
  }
  80%,
  99.9% {
    margin-top: 30%;
    margin-left: 80%;
  }
}

// You can set fade out timer here
.fadeOut {
  animation: 3s fadeOut;
  animation-fill-mode: forwards;
  visibility: hidden;
}

@keyframes fadeOut {
  0% {
    opacity: 1;
  }
  100% {
    visibility: visible;
    opacity: 0;
  }
}