Overriding notebook-stdlib by mbostock

index.html

<!DOCTYPE html>
<style>

#test {
  max-width: 480px;
  width: 50%;
  margin: auto;
  background: #ccc;
}

</style>
<div id="test"></div>
<script type="module">

import {Runtime, Inspector, Library} from "https://unpkg.com/@observablehq/notebook-runtime?module";
import notebook from "https://api.observablehq.com/d/bb5d3924d2e12f45.js?key=2e01d2649e1b85fa";

const test = document.querySelector("#test");

const stdlib = new Library;

const library = Object.assign({}, stdlib, {width});

function width() {
  return stdlib.Generators.observe(notify => {
    let width = notify(test.clientWidth);

    function resized() {
      let width1 = test.clientWidth;
      if (width1 !== width) notify(width = width1);
    }

    window.addEventListener("resize", resized);
    return () => window.removeEventListener("resize", resized);
  });
}

Runtime.load(notebook, library, cell => {
  if (cell.name === "test") {
    return new Inspector(test);
  }
});

</script>