loading.css

html,
body,
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  background: #252629;
  width: 100vw;
  min-height: 100vh;
  position: fixed;
  display: flex;
  justify-content: center;
  align-items: center;
}

.circle {
  width: 200px;
  height: 200px;
  border: 5px solid rgba(42, 192, 132, 0.08);
  border-radius: 50%;
  overflow: hidden;
  display: flex;
  justify-content: center;
  align-items: center;
  align-items: flex-end;
  position: relative;
}

.inner {
  width: 100%;
  height: 0px;
  background-color: rgba(42, 192, 132, 0.1);
  border-top-right-radius: 50%;
  border-top-left-radius: 50%;
}

.percent-container {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  color: #fff;
  font-weight: lighter;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 2rem;
  user-select: none;
}
.percent-container .percent {
  font-size: 1.1rem;
}

@keyframes startLoading {
  0% {
    height: 0px;
    background-color: rgba(42, 192, 132, 0.1);
  }
  100% {
    height: 200px;
    background-color: rgba(42, 192, 132, 0.3);
  }
}
@keyframes changeOpacityBorder {
  0% {
    border-color: rgba(42, 192, 132, 0.08);
  }
  100% {
    border-color: rgba(42, 192, 132, 0.7);
  }
}
.startLoading {
  animation-name: startLoading;
  animation-iteration-count: 1;
  animation-fill-mode: forwards;
  animation-timing-function: linear;
  animation-duration: 4s;
}

.borderOpacity {
  animation-name: changeOpacityBorder;
  animation-iteration-count: 1;
  animation-fill-mode: forwards;
  animation-timing-function: linear;
  animation-duration: 2s;
}