async function bundleCSS(options) {
  // Configure options for esbuild.
  const esBuildOptions = defaultESBuildOptions();
  esBuildOptions.entryPoints = await globby(options.filePaths);
  esBuildOptions.loader = {
    ".gif": "text",
    ".png": "text",
  };
  esBuildOptions.sourcemap = options.sourcemap;
  esBuildOptions.minify = options.minify;
  esBuildOptions.outdir = options.outdir;
  esBuildOptions.outbase = options.outbase;

  await esbuild.build(esBuildOptions);
}
Bundles CSS files.

@param {object} options
@param {string[]} options.filePaths The file paths to bundle.
@param {boolean} options.sourcemap
@param {boolean} options.minify
@param {string} options.outdir The output directory.
@param {string} options.outbase The