path

In page.html.twig you will have a working {{ base_path }} variable. Why it isn't available in every template, i have no idea. As i think it should be and everything else looks messy, my preferred solution is to do exactly as Drupal does in the preprocess page function for any place i need it.

Situation: You have lots of content that you don't really want in a menu at all, but you want to appear to be below or within a section of the site when you are viewing that content. For instance, when viewing news content the menu link for the overall views listing should appear to be active, or rather in the active path or trail.

We had a site that occasionally generated page not found errors for ie6_fixes.css. Occasionally, we realized, because this file was only sought by browsers following the hide-from-everything-except Internet Explorer 6 code. The file was then not being found because the name of the whole theme had changed, and the existing template had hard-coded in not just the location but also the name of the theme.

Changed in page.tpl.php (and all variations such as page-front.tpl.php and page-node-4.tpl.php:
@import "/sites/default/themes/jonas_theme/ie6_fixes.css";

Looking for the drupal path to your current theme? It can be helpful if you're making a theme and, for a change, you want to link directly to

print theme('stylesheet_import', base_path() . path_to_theme() ."/modules.css");

For our purposes, something like:

<img src="<?php echo base_path() . path_to_theme() . "/sample.png"; ?>" />

Now I'm not sure that "." in echo will work. Feel free to test it out for us!