<p class="text">
  Text is green, if browser supports 
  <code>grid-template-rows:masonry</code>.<br>
  It works in Firefox Nightly only in March 2021.
</p>
@supports (grid-template-rows: masonry) {
  .text {
    color: green;
  }
}

/* ETC (Formatting only): */

body {
  margin: 1.5em;
  font-size: 130%;
  font-family: sans-serif;
}

External CSS

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External JavaScript

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