Note the use of sidebars to indicate nesting without wasting much horizontal space. HN mobile devs, please take note! I like what you've done thus far to keep

Note the use of sidebars to indicate nesting without wasting much horizontal space. HN mobile devs, please take note! I like what you've done thus far to keep the mobile view compact, but it is hard to see the indentation. Sidebars may help, if kept grey and not too intrusive.