Hello readers,
If you want to make a preloader using HTML and CSS follow the below code:

Html

<div class="circle">
    <div class="inner">
        <div class="spot"></div>
    </div>
</div>
    <h1>loading...   </h1>

CSS

@-webkit-keyframes spin {
  0% {
    opacity: 0.25;
  }
  50% {
    opacity: 1;
    background: red;
  }
  100% {
    -webkit-transform: rotate(360deg);
            transform: rotate(360deg);
    opacity: 0.25;
  }
}
@keyframes spin {
  0% {
    opacity: 0.25;
  }
  50% {
    opacity: 1;
    background: red;
  }
  100% {
    -webkit-transform: rotate(360deg);
            transform: rotate(360deg);
    opacity: 0.25;
  }
}
@-webkit-keyframes strange {
  50% {
    margin: 0;
    width: 5em;
    height: 5em;
    background: red;
  }
}
@keyframes strange {
  50% {
    margin: 0;
    width: 5em;
    height: 5em;
    background: red;
  }
}
@-webkit-keyframes toggleO {
  50% {
    opacity: 0.5;
  }
}
@keyframes toggleO {
  50% {
    opacity: 0.5;
  }
}
body {
  padding-top: 4em;
  text-align: center;
}

h1 {
  color: red;
  font-size: 2em;
  font-family: courier;
  margin-top: 0.45em;
  -webkit-animation: toggleO 1s infinite linear;
          animation: toggleO 1s infinite linear;
}

.circle, .inner, .spot {
  border-radius: 50%;
  position: relative;
}

.circle {
  background: -webkit-linear-gradient(#000000, #000000);
  background: linear-gradient(#000000, #000000);
  height: 6em;
  width: 6em;
  display: inline-block;
  margin: 0 auto;
  -webkit-animation: spin 1s infinite linear;
          animation: spin 1s infinite linear;
}

.inner {
  padding: 0.2em;
  background: #fff;
  height: 4.5em;
  width: 4.5em;
}

.spot {
  margin-top: 1.4em;
  margin-left: 1.4em;
  height: 1em;
  width:  1em;
  background: red;
  -webkit-animation: strange 1s linear infinite;
          animation: strange 1s linear infinite;
}