Metronic supports full Dark Mode that you can preview here and easiliy setup following the below instructions.
--dark-modeflag in
											theme/tools/folder to generate the Dark Mode of CSS files.
											
gulp --dark-mode --demo1
													
npm run build --dark-mode --demo1
													style.dark.bundle.cssand
											plugins.dark.bundle.cssare generated in assets folder:
											
<!--begin::Global Stylesheets Bundle(used by all pages)-->
<link href="assets/plugins/global/plugins.dark.bundle.css" rel="stylesheet" type="text/css" />
<link href="assets/css/style.dark.bundle.css" rel="stylesheet" type="text/css" />
<!--end::Global Stylesheets Bundle-->
													dark-modeclass name to the
											<body>tag. Keep other
											bodyclass names.
											
<body class="dark-mode ...">
<!-- HTML content -->
</body>