.marquee {
  overflow: hidden;
  box-sizing: border-box;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 40px;
  width: auto;
  overflow: hidden;
  white-space: nowrap;
}

.marquee--inner {
  display: block;
  width: 233%;
  position: absolute;
  animation: marquee 25s linear infinite;
}

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

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