A CodePen by laithnurie. Try to Focus - Can easily cause headaches

index.html

<div class="container">
  <canvas></canvas>
  <p class="text">Try to F<span>o</span>cus</p>
</div>

script.js

var canvas = document.querySelector('canvas'),
ctx = canvas.getContext('2d'),
w = window.innerWidth,
h = window.innerHeight, 
points = 1000,
colors = ['#024a59','#04a65b','#04bf56','#f2cc5d','#f3574a'],
canvasPoints = [];

canvas.width = w;
canvas.height = h;
    
function Point(){
    this.x = Math.round(Math.random()*w);
    this.y = 100;
    this.r = Math.round(Math.random()*20)+5;
    this.opacity = Math.random();
    this.velocity = this.opacity*10;
    this.c = colors[Math.floor(Math.random()*5)];
} 

(function init(){
  for(var i = 0; i<points;i++){
    canvasPoints.push(new Point());
  }
})();


function draw(){
   ctx.clearRect(0,0,w,h);
   for(var i = 0; i<points;i++){
      ctx.globalCompositeOperation = 'lighter';
      var temp = canvasPoints[i];
      ctx.fillStyle = temp.c;
      ctx.globalAlpha = temp.opacity;
      ctx.beginPath();
      ctx.arc(temp.x,temp.y,temp.r,0,Math.PI*2,true);
      
      temp.y -= temp.velocity; 
      ctx.fill();
      
      if(temp.y<0)temp.y = h;
    } 
    
    requestAnimFrame(draw);
  }

window.requestAnimFrame = (function(){
  return  window.requestAnimationFrame       ||
          window.webkitRequestAnimationFrame ||
          window.mozRequestAnimationFrame    ||
          function( callback ){
            window.setTimeout(callback, 1000 / 60);
          };
})();

draw();

style.css

@import url(http://fonts.googleapis.com/css?family=Raleway:300);

*{margin:0}
.container{
  height:100%;
  width:100%;  
  position: relative;
}
canvas{
  background:#222;
  
}

.text{
  color:#0072c5;
  font:70px  'Raleway',Arial;
  letter-spacing:20px;
  position: absolute;  
  padding:20px 0;
  text-align:center;
  top:40%;
  transition:all 1s;
  width:100%;
}
span{
  color:transparent;
  text-shadow:0 0 10px #222,0 0 20px #0072c5;
}

.text:hover{
  letter-spacing:0px;
  background:#222;
 
}

.text:hover span{
  color:#0072c5;
  text-shadow:none;
}