Slim loading indicator CSS

loading_animation.css

@keyframes loading_animation {
  0% {
    width: 0;
  }
  20% {
    width: 80%;
  }
  100% {
    width: 90%;
  }
}

.loader {
    position: fixed;
    width: 100%;
    height: 3px;
    background: #ffffff;
    z-index: 10;
    top: 0;
    left: 0;
}

.loader .loader-inner {
    position: relative;
    display: block;
    height: 3px;
    background: #ff0000;
    animation: loading_animation 12s ease-out 1;
    width: 90%;
}

loading_animation.html

<div class="loader"><div class="loader-inner"></div></div>