*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
}

body {
  min-height: 100vh;
  display: grid;
  place-items: center;
  background-color: black;
  font-family: sans-serif;
}

.info {
  font-size: 0.8rem;
  letter-spacing: 2px;
  color: whitesmoke;
  text-align: center;
}

div {
  position: relative;
}

div > span {
  display: inline-block;
  width: 800px;
  height: 200px;
  border: 1px solid #000;
  border-radius: 10px;
  display: grid;
  place-items: center;
  font-size: 4rem;
  text-transform: uppercase;
  letter-spacing: 0.2em;

  /* background: red; */
  background: linear-gradient(90deg, black, white, black);
  background-repeat: no-repeat;
  background-position-x: -700px;
  
  /* transparent would hide text COMPLETELY */
  /* color: transparent; */
  /* but with slight opacity we can still see it... */
  color: rgba(255,255,255, 0.2);

  background-clip: text;
  -webkit-background-clip: text;
}

input[type="checkbox"] {
  opacity: 0;
  cursor: pointer;
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  appearance: none;
  /* put "checkbox" above the span, so we can click it */
  z-index: 1;
}

input:checked + span {
  animation: shine 4s linear 3.5 alternate forwards;
}


@keyframes shine {
  to {
    background-position-x: 700px;
  }
}