<div></div>
div {
  width: 100vw;
  height: 100vh;
  background-image: linear-gradient(
    to right,
    rgb(255 105 0) 33%,
    transparent 33%,
    transparent 66%,
    rgb(207 46 46) 66%,
    rgb(207 46 46) 100%
  );
}

External CSS

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External JavaScript

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