<div class="wrapper">
  <h3>[background-position]</h3>
  <div class="loading-bg"></div>
  <h3>[box-shadow]</h3>
  <div class="loading-bs"></div>
</div>

@import url('https://fonts.googleapis.com/css2?family=Space+Mono:wght@700&display=swap');

$color: #ffcc33;
$bezier: cubic-bezier(0, 0.02, 0.21, 2.87);
body {
  height: 100vh;
  background-color: #fcfcfc;
  display: flex;
  justify-content: center;
  align-items: center;
  font-family: 'Space Mono', monospace;
  h3 {
    text-decoration: underline;
  }
}
.wrapper {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
}
// ---------------------
// use background-position
// ---------------------
$bg-size: 40px;
$bg-jump: 25%;
.loading-bg {
  width: $bg-size * 4;
  height: 80px;
  margin-bottom: 20px;
  background: radial-gradient(circle, $color 50%, transparent 50%),
    radial-gradient(circle, $color 50%, transparent 50%),
    radial-gradient(circle, $color 50%, transparent 50%);
  background-repeat: no-repeat;
  background-size: $bg-size $bg-size;
  animation: bounce-bg 1.2s both infinite $bezier;
}
$part: 1 /6 * 100%;
@keyframes bounce-bg {
  0%, 100%, #{$part*2}, #{$part*4} {
    background-position: 0 50%, 50% 50%, 100% 50%;
  }
  #{$part*1} {
    background-position: 0 $bg-jump, 50% 50%, 100% 50%;
  }
  #{$part*3} {
    background-position: 0 50%, 50% $bg-jump, 100% 50%;
  }
  #{$part*5} {
    background-position: 0 50%, 50% 50%, 100% $bg-jump;
  }
}

// ---------------------
// use box-shadow
// ---------------------
$bs-size: 28px;
$distance1: $bs-size * 1;
$distance2: $bs-size * 3;
$distance3: $bs-size * 5;
$bs-jump: -$bs-size / 3;
.loading-bs {
  width: $bs-size;
  height: $bs-size;
  border-radius: 50%;
  margin: 24px auto;
  box-shadow: $distance1 0 0 $color, $distance2 0 0 $color, $distance3 0 0 $color;
  transform: translateX(-$distance2);
  animation: bounce-bs 1.2s both infinite $bezier;
}
@keyframes bounce-bs {
  0%, 100%, #{$part*2}, #{$part*4} {
    box-shadow: $distance1 0 0 $color, $distance2 0 0 $color, $distance3 0 0 $color;
  }
  #{$part*1} {
   box-shadow: $distance1 $bs-jump 0 $color, $distance2 0 0 $color, $distance3 0 0 $color;
  }
  #{$part*3} {
    box-shadow: $distance1 0 0 $color, $distance2 $bs-jump 0 $color, $distance3 0 0 $color;
  }
  #{$part*5} {
    box-shadow: $distance1 0 0 $color, $distance2 0 0 $color, $distance3 $bs-jump 0 $color;
  }
}