<div class="control">
  <label for="angle">Angle:</label>
  <input type="range" id="angle" name="angle" value="0" min="0" max="360" step="1" />
  <output id="output">0deg</output>
</div>
@import url("https://fonts.googleapis.com/css2?family=Exo:wght@600&display=swap");

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

body {
  width: 100vw;
  min-height: 100vh;
  font-family: "Exo", Arial, sans-serif;
  background-color: #222;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}

:root {
  --angle: 0deg;
}
body {
  background-image: conic-gradient(from var(--angle), #09f, #f36);
}
View Compiled
const rootElement = document.documentElement;
const angleInput = document.getElementById("angle");
const angleOutput = document.getElementById("output");

angleInput.addEventListener("input", (etv) => {
  rootElement.style.setProperty("--angle", `${etv.target.value}deg`);
  angleOutput.innerText = `${etv.target.value}deg`;
});
View Compiled

External CSS

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External JavaScript

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