USWDS 2.0

@fskreuz Thanks for the heads up. Are your changes based on the newly-created 8.x-2.0-alpha1 branch of this Drupal theme? Or are they based on the 8.x-1.0-beta3 branch? Just wanted to clarify that.

But either way you are always welcome to post a patch. That may be the best way to get the conversation started.

@fskreuz, thanks for posting the patch & for all the work you've done on this. I also have a patch for integrating the beta-6 changes which I will post up here so we can review how to merge both patches.
I am still reviewing your patch but thanks for catching the section in page.html.twig that has the page.help region commented out. That was an oversight.
I have a question about the addition on the block.html.twig template. From my understanding, this will cause all blocks to be rendered with a USWDS accordion component by default. Is that the intention?

+++ b/templates/system/block/block.html.twig
@@ -0,0 +1,56 @@
+......
+#}
+{%
+  set classes = [
+    'block',
+    'block-' ~ configuration.provider|clean_class,
+    'block-' ~ plugin_id|clean_class,
+    'usa-accordion',
+  ]
+%}
+
+{%
+  set titleClasses = [
+    'usa-accordion__heading'
+  ]
+%}
+
+<div{{ attributes.addClass(classes) }}>
+  {{ title_prefix }}
+  {% if label %}
+    <h2{{ title_attributes.addClass(titleClasses) }}>
+      <button class="usa-accordion__button">{{ label }}</button>
+    </h2>
+  {% endif %}
+  {{ title_suffix }}
+  {% block content %}
+    <div class="usa-accordion__content usa-prose">
+      {{ content }}
+    </div>
+  {% endblock %}
+</div>

This patch is Work-in-progress. The ideal fix for this issue should probably be a combination of both patches in #4 and #6. I'm currently working on merging them.

Thanks @fskreuz, that does make sense.
Making the blocks collapsible sounds like good feature to have. I will test it further locally.

Like @brockfanning suggested in other issues, it would be great to separate out the features like disabling the search box, collapsible blocks, removing the mobile menu region etc. into patches & attach them to their respective issues so they can be reviewed individually.

Once I am done with merging the 2 patches here into one patch that reflects just the USWDS beta-6 updates, I will create a new issue for collapsible blocks and add the new block template to it. Please let me know if you have some time to upload patches into any of the existing issues. If not, when I am done with the above 2 tasks I will also go ahead and try to separate the remaining code in your patch into the other issues.

I've applied the 3 patches in 3039814, 3040374, and 3039817 as well as #13 and haven't seen any issues so far. I also went through the release changes for the beta 7 release on https://v2.designsystem.digital.gov/about/releases/ and didn't see any breaking changes in the code with the four patches applied. Thanks @fskreuz, @irisibk, and @brockfanning for all of the work you've done!