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HTML 

              
                <header>
	<h1>CSS3 PONG!</h1>
</header>
  <div role="main">
      <div id="court">
          <input id="rd0" type="radio" name="set" checked>
          <input id="rd1" type="radio" name="set">        
          <input id="rd2" type="radio" name="set">        
          <input id="rd3" type="radio" name="set">        
          <input id="rd4" type="radio" name="set">        
          <input id="rd5" type="radio" name="set">      
	          <div id="horizontal">        
	             		<div id="ball"> </div>        
		                 	<div id="player2"> </div>      
	              </div>    
              <ul id="pl1"><!-- Player 1 score (Tip: um... it never changes ;) ) -->    
                  <li>0</li>       
                  <li>1</li>         
                  <li>2</li>       
                  <li>3</li>      
                  <li>4</li>      
                  <li>WINNER!</li>     
              </ul>    
              <ul id="pl2"><!-- Player 2 score -->       
                  <li>0</li>       
                  <li>1</li>         
                  <li>2</li>       
                  <li>3</li>      
                  <li>4</li>      
                  <li>WINNER!</li>     
              </ul>    
        	</div>    
      
      <p>Click ball to serve</p> 
    <p>Currently best viewed in Chrome</p>
      </div>  
      <footer>      
      <p><a href="http://www.sitepoint.com/css3-pong-insane-things-to-do-with-css/">SitePoint.com 2013 -  Alex Walker</a></p>  
      </footer>
!

CSS 

              
                @import "compass/css3";

@import url('https://fonts.googleapis.com/css2?family=Montserrat+Alternates:wght@500&display=swap');
/**
 * Playable Pong *
*/

$speed: 1.5; /* 1=fast 10=slow*/
$updown-speed:(1.9s*$speed);
$leftright-speed:(2.7s*$speed);
  
body {
  overflow: hidden;
  font-family: 'Montserrat Alternates', sans-serif;
  background: #000;
  margin: 0;
  padding: 0;
  color: #0f0;
  text-align: center;
  text-transform: uppercase;
   }

body:before { /* scanline effect - full screen */
  content: "";
  position: absolute;
  margin: 0;
  padding: 0;
  background-image: linear-gradient(transparent 50%, rgba(0, 40, 40, 0.25) 50%);
  background-size: 100% 4px;
  width: 100%;
  height: 100%;
  z-index: 999;
  pointer-events: none;
  top: 0;
  left: 0; }

body * { /* blur glow */
  text-shadow: 0px 0px 3px rgba(90, 255, 90, 0.9), 0px 0px 3px rgba(90, 255, 90, 0.9), 0px 0px 7px rgba(90, 255, 90, 0.9); }

h1 {
  text-align: center;
  font: 400 60px 'Impact';
  letter-spacing: 5px;
  font-family: 'Montserrat Alternates', sans-serif;
  line-height: 1em;
  color: #0afa0a;
  font-weight: bold;
  font-size: 70px;
  text-shadow: 0px 0px 0 #35bb35, 0px 1px 0 #47a947, 0px 2px 0 #589858, 0px 3px 0 #6a866a, 0px 4px 0 #7b757b, 0px 5px 0 #8c648c, 0px 6px 5px rgba(0, 0, 0, 0.25), 0px 6px 1px rgba(0, 0, 0, 0.5), 0px 0px 5px rgba(0, 0, 0, 0.2); }

p {
  text-align: center;
  font: 400 24px''; 
font-family: 'Montserrat Alternates', sans-serif;}

footer p {
  font-size: 12px; }

#court {
  margin: 29px auto;
  width: 600px;
  height: 301px;
  position: relative;
  border: 4px dotted #3f3;
  text-shadow: 0px 0px 7px rgba(90, 255, 90, 0.9), 0px 0px 7px rgba(90, 255, 90, 0.9);
cursor: url(https://i.imgur.com/OGNRZH1.gif), text;}

#court:before {    /* net */
  left: 50%;
  content: "";
  width: 10px;
  height: 300px;
  position: absolute;
  border-left: 4px dashed #3f3;
}

/* ------ ball components ------- */
#ball {
  position: absolute;
  width: 20px;
  height: 20px;
  display: block;
  background: #3f3;
  border-radius: 50%;
  cursor: url(https://i.imgur.com/OGNRZH1.gif), text;
  box-shadow: 0px 0px 7px rgba(90, 255, 90, 0.9), 0px 0px 7px rgba(90, 255, 90, 0.9);
  animation: fadein 2s 1 linear;
  transform: translate3d(10px, 0, 0); }

#horizontal {
  position: absolute;
  width: 100%;
  height: 20px;
  top: 45%; 
  cursor: url(https://i.imgur.com/OGNRZH1.gif), text;}

#player2 {
  /* player 2 */
  background: #3f3;
  position: absolute;
  width: 7px;
  height: 44px;
  right: 4px;
  margin-top: -12px; }

/* ------ ball animation ------- */
input:checked + input:hover ~ #horizontal #ball {
  /* ready: pulse ball  */
  animation: pulse 0.5s infinite; }

input:hover:checked ~ #horizontal {
  animation: updown $updown-speed infinite linear; }

input:hover:checked ~ #horizontal #ball {
  animation: leftright $leftright-speed infinite linear;
  background: cyan; }

input:hover:checked ~ #horizontal #player2 {
  animation: twitchy $leftright-speed infinite linear; }

/* ------ The Scoring System------- */
ul {
  position: absolute;
  right: 30%;
  list-style: none;
  height: 40px;
  width: 80px;
  overflow: hidden;
  font-size: 40px;
  padding: 0;
  margin: 0;
  top: 20px;
  text-align: center; }

ul li {
  position: absolute;
  top: -50px;
  width: 80px; }

/* position score lists */
ul#pl1 {
  left: 25%; }

ul#pl2 {
  left: 64%;
  width: 180px;
  text-align: left; 
}

ul#pl1 li:nth-of-type(1) {
  top: 0px; 
}

input:nth-of-type(1):checked ~ ul#pl2 li:nth-of-type(1),
input:nth-of-type(2):checked ~ ul#pl2 li:nth-of-type(2),
input:nth-of-type(3):checked ~ ul#pl2 li:nth-of-type(3),
input:nth-of-type(4):checked ~ ul#pl2 li:nth-of-type(4),
input:nth-of-type(5):checked ~ ul#pl2 li:nth-of-type(5),
input:nth-of-type(6):checked ~ ul#pl2 li:nth-of-type(6),
input:nth-of-type(2):hover:checked ~ ul#pl2 li:nth-of-type(1),
input:nth-of-type(3):hover:checked ~ ul#pl2 li:nth-of-type(2),
input:nth-of-type(4):hover:checked ~ ul#pl2 li:nth-of-type(3),
input:nth-of-type(5):hover:checked ~ ul#pl2 li:nth-of-type(4),
input:nth-of-type(6):hover:checked ~ ul#pl2 li:nth-of-type(5) {
  top: 0px;
  /* show the score (LI) associated with each input */
  transition: top 0.75s; 
}

input:nth-of-type(1):hover:checked ~ ul#pl2 li:nth-of-type(1), 
input:nth-of-type(2):hover:checked ~ ul#pl2 li:nth-of-type(2), 
input:nth-of-type(3):hover:checked ~ ul#pl2 li:nth-of-type(3), 
input:nth-of-type(4):hover:checked ~ ul#pl2 li:nth-of-type(4), 
input:nth-of-type(5):hover:checked ~ ul#pl2 li:nth-of-type(5), 
input:nth-of-type(6):hover:checked ~ ul#pl2 li:nth-of-type(6) {
  top: -50px;
  /* delay the next score offscreen WHILE the hover is active */ }

/* ------ Scoring switches ------- */
input {
  /* hide all */
  width: 0px;
  height: 0px;
  overflow: hidden;
  appearance: none;
  position: absolute;
  top: -100px;
  left: -10px;
  cursor: url(https://i.imgur.com/OGNRZH1.gif), text; }

input:checked + input {
  left: -20px;
  top: 36%;
  width: 70px;
  height: 50px;
  z-index: 99; }

input:hover:checked {
  /* uncomment the next line to get an idea how we're faking collision detection with CSS hover - yes it's a huge hack ;) */
  /*background: rgba(0, 0, 200, 0.3);*/
  left: -20px;
  top: 36%;
  width: 100px;
  height: 100px;
  outline: 0px none;
  animation: 
  updown $updown-speed infinite linear, 
  targetzone $leftright-speed infinite linear;
  z-index: 99;
 }

input:hover:checked + input {
  /* keep the NEXT targetzone hidden till previous hover state ends */
  left: 0px;
  top: -100px;
  width: 50px;
  height: 50px; }

/* ------ reset score button ------- */
input#rd0 {
  /* reset scores*/
  left: 550px;
  appearance: normal;
  width: 50px;
  height: 50px; }

input#rd0:hover:checked {
  animation: none; }

input#rd0:before {
  /* reset scores*/
  content: "Reset";
  color: white;
  font-size: 12px;
  height: 25px; }

/* ------ The Animations ------- */

@keyframes updown {
  0%, 50%, 100% {
    /*  the middle  */
    transform: translate3d(0, 0, 0); }

  25% {
    /*  the top  */
    transform: translate3d(0, 142px, 0); }

  75% {
    /* the bottom */
    transform: translate3d(0, -136px, 0); } }

@keyframes leftright {
  0%, 100% {
    /* left side */
    transform: translate3d(10px, 0, 0);
    width: 10px;
    /*squash ball*/
    height: 25px; }

  5%, 48%, 55%, 99% {
    /* unsquash ball */
    width: 20px;
    height: 20px; }

  50% {
    /* right side */
    transform: translate3d(580px, 0, 0);
    width: 10px;
    /*squash ball*/
    height: 35px; } }

@keyframes targetzone {
  /* ball in general play */
  0%, 96% {
    width: 800px;
    height: 700px;
    margin: -50% 0 0 -50%; }

  /* ball about to pass player 1's baseline */
  96.1%, 100% {
    width: 150px;
    height: 100px; 
    top:0;
    left:0;
    margin: 10% 0 0 -50px;}
}

@keyframes pulse {
  /* pulse the ball -- 'READY!' */
  0%, 100% {
    opacity: .2; }

  90% {
    opacity: 1; } }

@keyframes fadein {
  /* fades new ball in after each point */
  0% {
    height: 0; }

  90% {
    height: 0; }

  100% {
    height: 20px; } }

@keyframes twitchy {
  /* make player twitch like a real player  */
   0%,
  100% {
    transform: translate3d(0, 40px, 0); }



  20% {
     transform: translate3d(0, -25px, 0); }

  44% {
    transform: translate3d(0, 25px, 0); }
  46% {
     transform: translate3d(0, -15px, 0); }

  48% {
    transform: translate3d(0, 15px, 0); }

  50% {
    transform: translate3d(0, 0, 0); }

  70% {
    transform: translate3d(0, 60px, 0); }

  85% {
    transform: translate3d(0, -30px, 0); }
}
!

JS 

              
                /* nothing to see here... */
!
999px

Console