Configure footer as slim with edit link

[aduth]

Closes #167

This pull request seeks to add an "Edit this page" link to the footer of each page, modeled after the TTS Handbook.

Screenshots:

Before	After

Reference:

As separate tasks, it may be worth considering:

• Aligning on whether a "Return to top" link should be present
• Aligning on whether a "File an issue" link should be present

[aduth]

🤔 Not sure on the build error:

- ./_site/accessibility-scanning/index.html
 
  *  linking to internal hash # that does not exist (line 415)
 
     <a href="#">Return to top</a>

It doesn't seem this change should have had any impact. The footer was updated to use the slim configuration, but as best I can tell, the markup produced should be the same:

• https://github.com/18F/uswds-jekyll/blob/472991d/_includes/components/footer--slim.html#L12-L16
• https://github.com/18F/uswds-jekyll/blob/472991d/_includes/components/footer--medium.html#L12-L16

[aduth]

Still not sure why it would suddenly become a failure as of this pull request, but possible resolutions could include:

• Remove "Back to top" link. This is absent from the TTS Handbook, so would bring the two further into alignment anyways.
• Change "Back to top" link href to point to a valid ID. Ideally this would be changed in the base uswds-jekyll theme.
• Configure htmlproofer to ignore the invalid hash pattern (Ignore <a href="#"> when checking internal links gjtorikian/html-proofer#118 (comment)).

[ryanhofdotgov]

Dug up a recent-ish PR that fixed similar problem: #130
"[added] data-proofer-ignore attribute to the link"

[aduth]

@ryanhofdotgov Ah! I guess a custom footer--medium.html was implemented to overwrite the theme default. I'll plan to compare it to the default to see if there's any other differences to note. The file should probably be removed, or an equivalent one made for the slim style.

[aduth]

Here's the diff between the override and the base theme:

14c14
<       <a href="{{ footer.top.href | default: '#' }}" data-proofer-ignore>{{ footer.top.text | default: 'Return to top' }}</a>
---
>       <a href="{{ footer.top.href | default: '#' }}">{{ footer.top.text | default: 'Return to top' }}</a>
42c42
<   {% if footer.logos or footer.heading or footer.contact %}
---
>   {% if footer.logos or footer.heading or footer.contact or footer.edit_page %}
61a62,63
> 
>       {% if footer.contact %}
63,67c65,93
<         <ul class="usa-unstyled-list">
<           <li><a href="https://github.com/18F/uswds-jekyll">18F USWDS-Jekyll theme</a></li>
<           <li>Hosted by <a href="https://federalist.18f.gov/">Federalist</a></li>
<           <li>Maintained by <a href="https://18f.gsa.gov/">18F</a></li>
<         </ul>
---
>         {% assign social_links = site.data.footer.contact.social_links %}
>         {% if footer.contact.contact_links %}
>           {% for _link in social_links %}
>             <a class="usa-link-{{ _link.type | default: 'generic' }}" href="{% if _link.external == true %}{{ _link.href }}{% else %}{{ _link.href | relative_url }}{% endif %}">
>               <span>{{ _link.text }}</span>
>             </a>
>           {% endfor %}
>         {% endif %}
>         {% if footer.contact.heading %}
>           <h3 class="usa-footer-contact-heading">{{ footer.contact.heading }}</h3>
>           {% endif %}
>           {% if footer.contact.contact_links %}
>             <address>
>               {% assign contact_links = site.data.footer.contact.contact_links %}
>               {% for _link in contact_links %}
>                 <div class="usa-footer-primary-content usa-footer-contact_info">
>                   <p>
>                     <a href="{% if _link.external == true %}{{ _link.href }}{% else %}{{ _link.href | relative_url }}{% endif %}">
>                       {{ _link.text }}
>                     </a>
>                   </p>
>                 </div>
>               {% endfor %}
>             </address>
>         {% endif %}
>       {% endif %}
>       {% if footer.edit_page %}
>         {% include components/github-edit.html footer=footer path=page.path %}
>       {% endif %}

Some of it is explained by customizations (#130) and upstream updates (18F/uswds-jekyll@ce5ded4). It was originally added in 18F/frontend#208, but I can't tell what context there'd have been for overriding the base file.

I think if the goal is to align to the TTS Handbook, it shouldn't be much a concern to lose these navigation links customizations.

For the purpose of getting the build to pass, I could introduce an override file for the slim footer, with a similar fix as what was done in #130. I suspect the options in #172 (comment) would probably be more durable / maintainable. I'm leaning toward removing the "Return to top" link.

[aduth]

Relevant for the errors previously flagged by html-proofer: 18F/uswds-jekyll#191

[ryanhofdotgov]

Sounds reasonable to me – thanks! I think a lot of the little inconsistencies in this guide from years of divergence will get solved by just wholesale adopting most of the guide setup from one of the other repos and making that the reusable thing across most guides. Here's the most recent comprehensive discussion on that topic:
https://docs.google.com/document/d/1LCKZKqoEEYOCwntZpTbHp8bW7tdnPnmmKVJ-YNHAUy4/edit