o-k-i.net/eleventy.config.js

module.exports = function(eleventyConfig) {
  // Copy assets folders to output
  eleventyConfig.addPassthroughCopy("src/assets");

  // Copy SEO files
  eleventyConfig.addPassthroughCopy("src/robots.txt");
  eleventyConfig.addPassthroughCopy("src/sitemap.xml");

  // Watch CSS files for changes
  eleventyConfig.addWatchTarget("src/assets/css/");

  // Watch JS files for changes
  eleventyConfig.addWatchTarget("src/assets/js/");

  // Configure browser sync to reload on CSS changes
  eleventyConfig.setBrowserSyncConfig({
    files: ['_site/assets/css/**/*.css', '_site/assets/js/**/*.js']
  });

  return {
    dir: {
      input: "src",
      output: "_site",
      includes: "_includes",
      data: "_data"
    },
    templateFormats: ["html", "md", "njk", "liquid"],
    htmlTemplateEngine: "njk",
    markdownTemplateEngine: "njk"
  };
};