<div id="app">
  <div id="wrapper">
    <!-- Make sure data-text equals the text you put inside the tags. -->
    <h1 class="glitch" data-text="
glitch">glitch</h1>
    <span class="sub">EFFECT</span>
  </div>
</div>

// Ignore all of this, scroll down until you see the next comment.
// I just like my eye candy. 
@import url('https://fonts.googleapis.com/css?family=Montserrat:100');


html, body, h1 {
  padding: 0;
  margin: 0;
  font-family: 'Montserrat', sans-serif;
}

#app {
  background: rgb(10,10,10);
  height: 100vh;
  width: 100%;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background: linear-gradient(rgba(10,10,10,.6),rgba(0,0,0,.9)), repeating-linear-gradient(0, transparent, transparent 2px, black 3px, black 3px),
    url('https://images.unsplash.com/photo-1506399558188-acca6f8cbf41?ixlib=rb-0.3.5&q=85&fm=jpg&crop=entropy&cs=srgb&ixid=eyJhcHBfaWQiOjE0NTg5fQ&s=7118759521e3184778a3b5e010e202c6');
  background-size: cover;
  background-position: center;
  z-index: 1;
}

#wrapper {
   text-align: center;
}

.sub {
  color: rgb(100,220,220);
  letter-spacing: 1em;
}

// Here's the meat and potatoes.

/* Our mixin positions a copy of our text
directly on our existing text, while
also setting content to the appropriate
text set in the data-text attribute. */
@mixin glitchCopy { 
    content: attr(data-text);
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.glitch {
  position: relative;
  color: white;
  font-size: 4em;
  letter-spacing: .5em;
  /* Animation provies a slight random skew. Check bottom of doc
  for more information on how to random skew. */
  animation: glitch-skew 1s infinite linear alternate-reverse;
  
  // Creates a copy before our text. 
  &::before{
    // Duplicates our text with the mixin.
    @include glitchCopy;
    // Scoots text slightly to the left for the color offset.
    left: 2px;
    // Creates the color 'shadow' that happens on the glitch.
    text-shadow: -2px 0 #ff00c1;
    /* Creates an initial clip for our glitch. This works in
    a typical top,right,bottom,left fashion and creates a mask
    to only show a certain part of the glitch at a time. */
    clip: rect(44px, 450px, 56px, 0);
    /* Runs our glitch-anim defined below to run in a 5s loop, infinitely,
    with an alternating animation to keep things fresh. */
    animation: glitch-anim 5s infinite linear alternate-reverse;
  }
  
  // Creates a copy after our text. Note comments from ::before.
  &::after {
    @include glitchCopy;
    left: -2px;
    text-shadow: -2px 0 #00fff9, 2px 2px #ff00c1;
    animation: glitch-anim2 1s infinite linear alternate-reverse;
  }
}

/* Creates an animation with 20 steaps. For each step, it calculates 
a percentage for the specific step. It then generates a random clip
box to be used for the random glitch effect. Also adds a very subtle
skew to change the 'thickness' of the glitch.*/
@keyframes glitch-anim {
  $steps: 20;
  @for $i from 0 through $steps {
    #{percentage($i*(1/$steps))} {
      clip: rect(random(100)+px, 9999px, random(100)+px, 0);
      transform: skew((random(100) / 100) + deg);
    }
  }
}

// Same deal, just duplicated for ultra randomness.
@keyframes glitch-anim2 {
  $steps: 20;
  @for $i from 0 through $steps {
    #{percentage($i*(1/$steps))} {
      clip: rect(random(100)+px, 9999px, random(100)+px, 0);
      transform: skew((random(100) / 100) + deg);
    }
  }
}

// Does the same deal as before, but now only skews. Used for main text.
@keyframes glitch-skew {
  $steps: 10;
  @for $i from 0 through $steps {
    #{percentage($i*(1/$steps))} {
      transform: skew((random(10) - 5) + deg);
    }
  }
}