<section>
<div class="container">
<kbd>animation-fill-mode: forwards;</kbd>
<ul>
  <li></li>
  <li></li>
  <li></li>
</ul>
</div>
<div class="container1">
<kbd>animation-fill-mode: backwards;</kbd>
<ul>
  <li></li>
  <li></li>
  <li></li>
</ul>
</div>
  <div class="container2">
<kbd>animation-fill-mode: <br>both;</kbd>
<ul>
  <li></li>
  <li></li>
  <li></li>
</ul>
</div>
  <footer><p>Обновите страницу или нажмите кнопку RERUN, чтобы просмотреть анимацию</p></footer>
</section>

body {
  margin: 0;
  background-image: 
linear-gradient(-45deg, transparent 50%, #E8E8E4 50%, #E8E8E4 55%, transparent 55%), 
linear-gradient(-45deg, #E8E8E4 5%, transparent 5%);
background-color: #FEFFFE;
background-size: 1em 1em;
}
kbd {
  display: block;
}
section {
  width: 660px;
  margin: 0 auto;
  overflow: hidden;
}
.container, .container1, .container2 {
  padding: 30px 0 20px;
  width: 210px;
  text-align: center;
  float: left;
}
ul {
  list-style: none;
  padding: 10px;
  display: inline-block;
  background: #3C4147;
  border-radius: 10px;
  box-shadow: inset 2px 2px 5px rgba(0,0,0,.7), 2px 2px 1px #3C4147;
}
li {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: black; 
  box-shadow: inset 2px 2px 4px rgba(0,0,0,.4), inset -2px -2px 4px rgba(255,255,255,.6);
}
@keyframes traffic {
 100%{background: #FB000D;}
}
@keyframes traffic1 {
  100%{background: #FED21D;}
}
@keyframes traffic2 {
  100%{background: #7DFA04;}
}
li:nth-of-type(1) {
  margin-bottom:5px;
  animation: traffic 2s forwards;
}
li:nth-of-type(2) {
  margin-bottom: 5px;
  animation: traffic1 2s forwards 2s;
}
li:nth-of-type(3) {
  animation: traffic2 2s forwards 4s;
}

.container1 li:nth-of-type(1) {
  margin-bottom:5px;
  animation: traffic 2s backwards;
}
.container1 li:nth-of-type(2) {
  margin-bottom: 5px;
  animation: traffic1 2s backwards 2s;
}
.container1 li:nth-of-type(3) {
  animation: traffic2 2s backwards 4s;
}
.container2 li:nth-of-type(1) {
  margin-bottom:5px;
  animation: traffic 2s both;
}
.container2 li:nth-of-type(2) {
  margin-bottom: 5px;
  animation: traffic1 2s both 2s;
}
.container3 li:nth-of-type(3) {
  animation: traffic2 2s both 4s;
}
footer {
  clear: both;
  text-align: center;
  padding: 20px 0;
  font: 14px/1.5 arial;
  background: #C8C2B7;
  border-top: 3px solid #6D6D6D;
  color: #6D6D6D;
}
p{margin:0}