.barra{
  margin:0 ; height:20px; width: 30%; background: gray; border-radius: 50px; overflow: hidden
}

.progreso{
  display:block; width:50%; height: 100%; border-radius:50px; background-image: linear-gradient(-45deg, yellow 25%, green 25%, green 50%, yellow 50%, yellow 75%, green 75%, green 25%); background-size: 50px 50px; animation: load 1s infinite linear
}

@keyframes load {
  0% { background-position:0 0}
  100% {
    background-position:50px 50px
  }
}