[meta] Goals for core themes: Make Stark as semantic as possible; Make Bartik a better prospective base theme

Problem/Motivation

Default core markup (aka Stark) is messy. For example, theme_item_list() includes:

  $output = '<div class="item-list">';
  if (isset($title) && $title !== '') {
    $output .= '<h3>' . $title . '</h3>';
  }

which is arguably unnecessary and superfluous. Given that we are converting the entire core markup to Twig in the new theme system, this presents an opportunity to remove things that may not be necessary. Whether Twig makes it into D8 or not, we'd like to see a big clean-up in Stark, and improvement of Bartik.

We've been using the "theme system cleanup" tag to track things like this in general, but this issue could establish some directions and goals for the themes.

Proposed resolution

After some discussion at the 2012 BADCamp Twig Sprint we expressed a desire to have core default markup (i.e. what Stark provides) to be as barebones as possible. Thus, the target audience for using stark would be those themers who truly want to start with a clean slate, and don't wish to have to work backwards to reach that slate.

Accordingly, we'd like to see Bartik become a better prospect for a base theme so that it is easy to start with and build from.

For example, move some of the functionality from theme.inc to Bartik's template.php. Or have stark contain no regions (aside from content) by default.

Remaining tasks

#1842140: Remove title and wrapper div from item-list.html.twig
#1854672: remove seven_node_add_list() from core (update the markup in theme_node_add_list() instead)
@todo: Add sub issues to this list.

User interface changes

None, at the moment. Regions may disappear in Stark.

API changes

TBD

Related Issues

#1843798: [meta] Refactor Render API to be OO
#1804614: [meta] Consolidate theme functions and properly use theme suggestions in core
#1804488: [meta] Introduce a Theme Component Library
#1499460: [meta] New theme system
#1087784: Add new theme to Drupal 8.1.x or another minor version
#912458: Design Initiative: Core theme selection and development process
#737136: Put together a list of must-have features for new core themes and set a final deadline for implementing them