Circular loader (using linear-gradient, pseudo-element and span)

by Konstantin Rouda

HTML

<div class="loader">

  <div class="loader-helper loader--fail">
   
    <div class="sign">
        <span class="border-helper border-helper--bottom"></span>
        <span class="border-helper border-helper--right"></span>
    </div>

  </div>
  
</div>

CSS

HTML {
  font-size: 100%;
  line-height: 1.5;
  font-family: "Droid Sans", "Open Sans", sans-serif;
  box-sizing: border-box;
}

BODY {
  display: flex;
  flex-flow: column wrap;
  margin: 0;
  color: rgb(81, 85, 88);
  min-height: 100vh;
  background: rgb(244, 235, 236) url(http://imgh.us/cactus-sm.jpg) no-repeat;
  //background: rgba(76, 68, 69, 0.68)  url(http://imgh.us/cactus-sm.jpg) no-repeat;
  background-position: calc(100% + 203px) bottom; /*203px - half width of the image*/
}

*, *::before, *::after {
  box-sizing: inherit;
  color: inherit;
}


.loader {
  position: relative;
  width: 300px;
  height: 300px;
  margin: 2em auto 0;
  background-color: rgb(234, 225, 226);
  //background-color:  rgba(128, 124, 125, 1);
  //background-color: rgb(200, 250, 250);
  background-image: linear-gradient(to right, transparent 50%, indianred 0);
  color: transparent;
  border-radius: 50%;
  overflow: hidden;
  transform: scale(0);
  //box-shadow: 0px 2px 4px rgba(20, 20, 20, .3);
  text-align: center;
  animation: loader-appear 1s ease-in-out 1 forwards;
}

@keyframes loader-appear {
  50% { transform: scale(1.2); }
  
  100% { transform: scale(1); }
}

.loader::before {
  content: "";
  position: absolute;
  top: 0; left: 50%;
  width: 50%; height: 100%;
  border-radius: 0 100% 100% 0 / 50%;
  background-color: inherit;
  transform-origin: left;
  animation: loader-spin 3s linear 2, loader-bg 6s step-end 1;
  animation-fill-mode: forwards;
}

.loader-helper {
  content: "";
  position: absolute;
  top: 50%; left: 50%;
  width: 95%; height: 95%;
  border-radius: 50%;
  transform: translate(-50%, -50%);
  background-color: inherit;
  text-align: center;
}





@keyframes loader-spin {
  100% { transform: rotate(.5turn); }
}

@keyframes loader-bg {
  50%, 100% { background: indianred; }
}

.sign {
  position: relative;
  display: inline-block;
  width: 65px;
  height: 100px;
  margin: 20% auto;
  transform: rotate(45deg);
}


.border-helper {
  position: absolute;
 ...