.marquee {
  width: 100%;
  overflow: hidden;
  white-space: nowrap;
  box-sizing: border-box;
}

.marquee span {
  display: inline-block;
  padding-left: 100%;
  animation: marquee 15s linear infinite;
}

@keyframes marquee {
  0%   { transform: translateX(0); }
  100% { transform: translateX(-100%); }
}