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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

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JavaScript

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Babel includes JSX processing.

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HTML 

              
                <main>
  <div></div>
</main>
<aside>
  <div class="scrubber-container">
    <label for="scrubber">Sides</label>
    <input id="scrubber" type="range" min="3" max="60" value="40" step="1" />
    <output for="scrubber"><b>40</b></output>
  </div>
</aside>
!

CSS 

              
                main div {
  margin: 5vmin auto;
  width: 70vmin;
  height: 70vmin;
  position: relative;
  --center: 50%;
  --radius: 50%;
  box-sizing: border-box;
}
main div::before {
  position: absolute;
  inset: 0;
  border: 0.5vmin dashed hsl(176 100% 64% / 40%);
  content: "";
}
main div::after {
  position: absolute;
  inset: 0;
  content: "";
  background: linear-gradient(135deg, hsl(196 100% 64%), hsl(176 100% 64%));
  clip-path: var(--clipped);
}
p {
  border-radius: 50%;
  font-size: 0.5rem;
  font-size: system-ui, sans-serif;
}
main {
  flex: 1;
}

body {
  height: 100vh;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  margin: 0;
  padding: 0;
  background: linear-gradient(45deg, hsl(344 100% 50%), hsl(234 100% 60%));
  /*
  background: conic-gradient(from 90deg at 50% 30vmin, hsl(334 100% 60%), hsl(284 100% 60%), hsl(244 100% 60%), hsl(44 100% 60%)); */
}
aside {
  color: white;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  align-items: center;
  left: 0;
  right: 0;
  padding: 0.5rem 1rem 0;
  background: hsl(223 100% 3% / 87%);
  backdrop-filter: blur(8px);
  font-family: system-ui, sans-serif;
  border-top: 0.5vmin solid hsl(343 100% 60%);
}
.scrubbable .scrubber-container {
  opacity: 1;
}
label {
  padding-right: 0.5rem;
}
.scrubber-container {
  display: flex;
  justify-content: center;
  align-items: center;
  opacity: 0;
  transition: opacity 400ms ease-out;
}
output {
  font-family: monospace;
  overflow-y: auto;
  padding: 1rem 0.5rem 1rem;
}
!

JS 

              
                const div = document.querySelector("div");
const output = document.querySelector("output");
const minSides = 3;

const supportsCssMath = window?.CSS?.supports("width: calc(sin(0deg) * 1vw)");

if (supportsCssMath) {
  div.classList.add("css-math-supported");
  finalPoints = generateViaCss();
  setupInteraction();
} else {
  document.querySelector("aside").textContent =
    "CSS Trig Functions are not supported in this browser. Please try the latest version of Safari, Firefox, Edge, or Chrome.";
}

function generateViaCss() {
  let points = [];

  for (let i = minSides; i <= 60; i++) {
    points.push(generateNSides(i));
  }

  return points;
}

function generateNSides(n) {
  let points = [];

  for (let i = 0; i < n; i++) {
    points.push(
      `calc(var(--center) + (cos(${
        (i / n) * 360
      }deg) * var(--radius))) calc(var(--center) + (sin(${
        (i / n) * 360
      }deg) * var(--radius)))`
    );
  }

  return `polygon(evenodd, ${points.join(",")})`;
}

function setupInteraction() {
  scrubber.setAttribute("max", finalPoints.length + minSides - 1);
  //scrubber.setAttribute("value", finalPoints.length);

  const pathLength = finalPoints.length;

  document.body.classList.add("scrubbable");

  scrubber.addEventListener("input", updateOutput);

  function updateOutput() {
    const step = scrubber.value;
    div.style.setProperty(
      "--clipped",
      finalPoints[parseInt(step, 10) - minSides]
    );

    document.querySelectorAll("output");
    output.textContent = step;
  }

  updateOutput();
}
!
999px

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