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About the <head>

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Insecure Resource

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CSS

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CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.

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CSS Base

About CSS Base

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JavaScript

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JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

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Babel includes JSX processing.

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HTML 

              
                <main>
  <section>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <span></span>
  </section>
  <section class="spinning">
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <span></span>
  </section>
</main>

<form>
  <p>
    <label for="rate">Playback Rate</label>
    <input type="range" id="rate" min="-1" max="1" step=".05" value="1" />
    <output id="rate-output" for="rate">Current: 1x</output>
  </p>
  <p>
    <label for="opacity">Half Circle Opacity</label>
    <input type="range" id="opacity" min="0" max="1" step=".025" value="1" />
    <output id="opacity-output" for="opacity">Current: 1</output>
  </p>
</form>
!

CSS 

              
                section {
  --dim: 45vmin;
  margin: 2.5vmin;
  --num: 20;
  width: var(--dim);
  height: var(--dim);
  position: relative;
}
.no-waapi .spinning {
  animation: spin 9700ms infinite linear;
  animation-duration: calc(16.66666666667 * 6ms);
}
div {
  position: absolute;
  width: var(--diameter, var(--dim));
  height: var(--diameter, var(--dim));
  background: hsl(0, 100%, 98%);
  border-radius: 50%;
  color: hsl(220, 100%, 43%);
  color: black;
  border: calc(var(--dim) / 75) solid currentColor;
  left: 50%;
  top: 50%;
  transform:
    translate(-50%, -50%)
    rotate(var(--rotate, 0deg));
}
div:nth-of-type(1) {
  border:none;
}
div:nth-of-type(n+2) {
  //clip-path: polygon(0% 50%, 0% 21%, 50% 50%);
  clip-path: polygon(0% 50%, 0% 0%, 21% 0%, 50% 50%);
}
div:nth-of-type(2) {
  --diameter: calc(var(--dim) * 19 / var(--num));
}
div:nth-of-type(3) {
  --diameter: calc(var(--dim) * 18 / var(--num));
}
div:nth-of-type(4) {
  --diameter: calc(var(--dim) * 17 / var(--num));
}
div:nth-of-type(5) {
  --diameter: calc(var(--dim) * 16 / var(--num));
}
div:nth-of-type(6) {
  --diameter: calc(var(--dim) * 15 / var(--num));
}
div:nth-of-type(7) {
  --diameter: calc(var(--dim) * 14 / var(--num));
}
div:nth-of-type(8) {
  --diameter: calc(var(--dim) * 13 / var(--num));
}
div:nth-of-type(9) {
  --diameter: calc(var(--dim) * 12 / var(--num));
}
div:nth-of-type(10) {
  --diameter: calc(var(--dim) * 11 / var(--num));
}
div:nth-of-type(11) {
  --diameter: calc(var(--dim) * 10 / var(--num));
}
div:nth-of-type(12) {
  --diameter: calc(var(--dim) * 9 / var(--num));
}
div:nth-of-type(13) {
  --diameter: calc(var(--dim) * 8 / var(--num));
}
div:nth-of-type(14) {
  --diameter: calc(var(--dim) * 7 / var(--num));
}
div:nth-of-type(15) {
  --diameter: calc(var(--dim) * 6 / var(--num));
}
div:nth-of-type(16) {
  --diameter: calc(var(--dim) * 5 / var(--num));
}
div:nth-of-type(17) {
  --diameter: calc(var(--dim) * 4 / var(--num));
}
div:nth-of-type(18) {
  --diameter: calc(var(--dim) * 3 / var(--num));
}
div:nth-of-type(19) {
  --diameter: calc(var(--dim) * 2 / var(--num));
}

/* Different effects when bars are in different locations
/* */
div:nth-of-type(n+5) {
  --base-deg: 60deg;
  --rotate: calc(var(--base-deg) * .4);
}
div:nth-of-type(n+8) {
  --rotate: calc(var(--base-deg) * .8);
}
div:nth-of-type(n+11) {
  --rotate: calc(var(--base-deg) * 1.2);
}
div:nth-of-type(n+14) {
  --rotate: calc(var(--base-deg) * 1.6);
}
div:nth-of-type(n+17) {
  --rotate: calc(var(--base-deg) * 2);
}
/**/


div:nth-of-type(20) {
  //display:none;
  --rotate: 0deg;
  border: none;
  background: currentColor;
  //background: hsl(340,80%,98%);
  opacity: var(--half-opacity, 1);
  clip-path: polygon(0% 50%, 100% 50%, 100% 100%, 0% 100%);
}

@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

span {
  display: block;
  position:absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: hsl(223, 84%, 13%);
  width: calc(var(--dim) / 24);
  height: calc(var(--dim) / 24);
  border-radius: 50%;
}

main {
  display: flex;
  justify-content: center;
  align-items: center;
  flex: 1;
}

body {
  background: hsl(223, 84%, 13%);
  height: 100vh;
  display: flex;
  flex-direction: column-reverse;
  justify-content: center;
  align-items: stretch;
  overflow: hidden;
}
*, *::before, *::after {
  box-sizing: border-box;
}


form {
  padding: 1rem;
  color: #fdfeff;
  font-family: system-ui, 'Segoe UI', -apple-system, sans-serif;
  background: hsla(0, 0%, 0%, .2);
  display: flex;
  justify-content: space-between;
}
form p {
  display: flex;
  flex-direction: column;
}
input[type=range] {
  max-width: 15rem;
}
.no-waapi form {
  display: none;
}
!

JS 

              
                const spinningTop = document.querySelector('.spinning');

//If Web Animations API is supported, allow playback control
if (spinningTop.animate) {
  //Soon CSS Animations will be exposed to WAAPI controls, but no stable browser supports it yet, so will just recreate CSS animation in WAAPI for better support now.
  
  let animation = spinningTop.animate({
    transform: ['rotate(0deg)', 'rotate(360deg)']
  }, {
    duration: 100,
    iterations: Infinity
  });
  
  let output = document.getElementById('rate-output');
  let outputOpacity = document.getElementById('opacity-output');
  
  document.getElementById('rate').addEventListener('input', function(e) {
    var value = parseFloat(e.currentTarget.value);
    if (animation.updatePlaybackRate) {
      animation.updatePlaybackRate(value);
    } else {
      animation.playbackRate = value;
    }
    output.value = `Current: ${value}x`;
  });
  
  document.getElementById('opacity').addEventListener('input', function(e) {
    let value = e.currentTarget.value;
    document.documentElement.style.setProperty('--half-opacity', value);
    outputOpacity.value = `Current: ${value}`;
  });
} else {
  document.documentElement.classList.add('no-waapi');
}
!
999px

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