<div class="marquee">
  <div class="marquee--inner">
    <span>
      <div class="orb"></div><div class="orb red"></div><div class="orb yellow"></div><div class="orb blue"></div><div class="orb orange"></div><div class="orb purple"></div><div class="orb green"></div><div class="orb"></div>
    </span>
    <span>
      <div class="orb"></div><div class="orb red"></div><div class="orb yellow"></div><div class="orb blue"></div><div class="orb orange"></div><div class="orb purple"></div><div class="orb green"></div><div class="orb"></div>
    </span>

  </div>
</div>

body {
  margin: 0;
  font-size: 42px;
  font-family: sans-serif;
  color: #333;
  overflow: hidden;
}

.orb {
  width: 50px;
  height: 50px;
  background: #999;
  border-radius: 50px;
  display: inline-block;
  margin: 0 24.7px;
  float: left;
  transition: all .2s ease-out;
}

.orb:hover {
  transform: scale(1.2);
  opacity: .5;
  cursor: pointer;
}

.red {background:red;}
.yellow {background:yellow;}
.blue {background:blue;}
.orange {background:orange;}
.purple {background:purple;}
.green {background:green;}

.marquee {
  height: 200px;
  width: 800px;
  border: 2px solid #eee;
  overflow: hidden;
  box-sizing: border-box;
  position: relative;
  margin: 200px auto;
}

.marquee--inner {
  display: block;
  width: 200%;
  margin: 70px 0;
  position: absolute;
  animation: marquee 20s linear infinite;
}

.marquee--inner:hover {
  animation-play-state: paused;
}

/*.half {
  float: left;
  width: 10%;
}*/

span {
  float: left;
  width: 50%:
}

@keyframes marquee {
  0% { left: 0; }
  100% { left: -100%; }
}

// Notes
//
// The total width of all items within span must = the width of the marquee
//
// Marquee div must be a fixed width :(
//
// The span must occur twice in order for the infinite scroll illusion to work