.test {
  width: 500px;
  height: 100px;
  background-color: #ccc;
  position: relative;
}

.test:before,
.test:after {
  content: "";
  position: absolute;
  left: 0px;
  right: 0px;
  height: 10px;
  background-image: -webkit-linear-gradient(0deg, red 20px, blue 20px, blue 40px, yellow 40px, yellow 60px, green 60px, green 80px);
  background-image: -ms-linear-gradient(0deg, red 20px, blue 20px, blue 40px, yellow 40px, yellow 60px, green 60px, green 80px);
  background-size: 80px;
}

.test:before {
  top: 0px;
}

.test:after {
  bottom: 0px;
}