Simple animated skeleton in Sass & CSS

skeleton.scss

// Sass
.skeleton {
  display: inline-block;
  height: 1em;
  position: relative;
  overflow: hidden;
  background-color: #dddbdd;

  &::after {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    transform: translateX(-100%);
    background-image: linear-gradient(
      90deg,
      rgba(#fff, 0) 0,
      rgba(#fff, 0.2) 20%,
      rgba(#fff, 0.5) 60%,
      rgba(#fff, 0)
    );
    animation: shimmer 5s infinite;
    content: "";
  }

  @keyframes shimmer {
    100% {
      transform: translateX(100%);
    }
  }

  &--card {
    width: 100%;
    height: 300px;
  }

  &--rounded {
    border-radius: 5px;
  }
}

// CSS
.skeleton {
  display: inline-block;
  height: 1em;
  position: relative;
  overflow: hidden;
  background-color: #dddbdd;
}

.skeleton::after {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  transform: translateX(-100%);
  background-image: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0) 0,
    rgba(255, 255, 255, 0.2) 20%,
    rgba(255, 255, 255, 0.5) 60%,
    rgba(255, 255, 255, 0)
  );
  animation: shimmer 5s infinite;
  content: "";
}

@keyframes shimmer {
  100% {
    transform: translateX(100%);
  }
}

.skeleton--card {
  width: 100%;
  height: 300px;
}

.skeleton--rounded {
  border-radius: 5px;
}