<div class="card">
  Conic Gradient Border
</div>
.card {
  inline-size: 50vmin;
  block-size: 50vmin;

  border: 5vmin solid hsl(100 100% 60%);
  border-image-slice: 1;
  
  /*  leverage cascade for cross-browser gradients  */
  border-image-source: linear-gradient(
    hsl(100 100% 60%),
    50%,
    hsl(200 100% 60%)
  );
  border-image-source: radial-gradient(
    hsl(100 100% 60%),
    75%,
    hsl(200 100% 60%)
  );
  border-image-source: conic-gradient(
    hsl(100 100% 60%), 
    hsl(200 100% 60%),
    hsl(100 100% 60%)
  );
  
  display: grid;
  place-content: center;
  padding: 4ch;
  box-sizing: border-box;
  font-size: 10vmin;
}

html {
  block-size: 100%;
  inline-size: 100%;
}

body {
  min-block-size: 100%;
  min-inline-size: 100%;
  background: hsl(204 100% 5%);
  color: white;
  margin: 0;
  display: grid;
  place-content: center;
  font-family: system-ui;
}

External CSS

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External JavaScript

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