Add help text to Archive.org borrowable links (#634)

* Add help text to Archive.org borrowable links

Add a collapsible help tip (similar to the existing WorldCat tip) for
Archive.org links that are borrowables (identified by /mode/ in URL).
The tip explains that the book can be borrowed for free and links to
Archive.org's official borrowing guide.

Fixes #613

Signed-off-by: Tim Ren <137012659+xr843@users.noreply.github.com>

* Simplify Archive.org help text per review feedback

- Remove redundant book-reader icon and arrow from help text
- Simplify wording to: "Reading this book on Archive.org may require a free account. Learn more"
- Remove target="_blank" from learn more link for consistency

Signed-off-by: Tim Ren <137012659+xr843@users.noreply.github.com>

* Fix link styling: add underline to Learn more link

Ensure the link is visually distinguishable on both dark and white
backgrounds by adding text-decoration: underline.

Signed-off-by: Tim Ren <137012659+xr843@users.noreply.github.com>

* Fix link styling via SCSS instead of inline style

Move link underline styling from inline style to the existing
.content_links .copyright div rule in content-perma.scss.
Use color: inherit so the link matches surrounding text on
both dark and white backgrounds.

Signed-off-by: Tim Ren <137012659+xr843@users.noreply.github.com>

* Fix font-family: inherit serif font for help text link

The .content_links a rule sets sans-serif font-family globally.
Override with font-family: inherit so the Learn more link matches
the surrounding serif body text.

Signed-off-by: Tim Ren <137012659+xr843@users.noreply.github.com>

* Move link styling to nimitta.scss for global coverage

The previous fix in content-perma.scss only applied to content pages,
not tag pages. Move the .copyright div a override into nimitta.scss
(inside .content_links) so it applies everywhere. Revert
content-perma.scss to its original state.

Signed-off-by: Tim Ren <137012659+xr843@users.noreply.github.com>

* Add target=_blank back to Learn more link

Signed-off-by: Tim Ren <137012659+xr843@users.noreply.github.com>

---------

Signed-off-by: Tim Ren <137012659+xr843@users.noreply.github.com>

Author: xr843

_includes/content_filelinks.html

@@ -2,7 +2,15 @@
   <div class="the-links">
      {% if include.content.external_url %}{% assign linkfmt = "" %}
         {%- capture linkbody -%}<i class="fa{% if include.content.external_url contains "youtu" %}{% assign linkfmt = "YouTube (link)" %}b fa-youtube"></i> YouTube{% elsif include.content.external_url contains "//www.academia.edu/" %}c-academia"></i>cademia.edu{% assign linkfmt = "Academia.edu" %}{% else %}s fa-{% assign ext = include.content.external_url | slice: -4, 4 %}{% if ext == ".mp3" %}{% assign linkfmt = "mp3" %}file-audio"></i> mp3{% elsif ext == ".zip" %}{% assign linkfmt = "zip" %}file-archive"></i> zip{% elsif ext == "epub" %}{% assign linkfmt = "epub" %}tablet-screen-button"></i> epub{% elsif ext == ".htm" or ext == "html" %}{% assign linkfmt = "html" %}globe"></i> Online{% elsif include.content.external_url contains "download" or include.content.external_url contains "viewcontent.cgi" or include.content.external_url contains "pdf" %}{% assign linkfmt = "pdf" %}file-pdf"></i> pdf{% else %}{% case include.content.category %}{% when "av" %}{% if page.subcat == "film" %}video{% else %}volume-up{% endif %}{% when "booklets" %}book-open{% when "monographs" %}book-open{% else %}globe{% endcase %}"></i> Online{% endif %}{% endif %}{%- endcapture -%}
-        <div class="a-link"><a class="btn" {% if include.newtab %}target="_blank"{% endif %} {% include content_link_data_attributes.html content=include.content linktype="Main External URL" linkfmt=linkfmt %} href="{{ include.content.external_url }}"{% for nrh in site.data.content.noreferrerhosts %}{% if include.content.external_url contains nrh %} rel="noreferrer"{% break %}{% endif %}{% endfor %}>{{ linkbody }}</a></div>
+        {%- assign is_archive_borrow = false -%}
+        {%- if include.content.external_url contains "archive.org" and include.content.external_url contains "/mode/" and include.content.category == "monographs" -%}
+            {%- assign is_archive_borrow = true -%}
+        {%- endif -%}
+        <div class="a-link">{% if is_archive_borrow %}<details class="copyright details-reset"><summary>{% endif %}<a class="btn" {% if include.newtab %}target="_blank"{% endif %} {% include content_link_data_attributes.html content=include.content linktype="Main External URL" linkfmt=linkfmt %} href="{{ include.content.external_url }}"{% for nrh in site.data.content.noreferrerhosts %}{% if include.content.external_url contains nrh %} rel="noreferrer"{% break %}{% endif %}{% endfor %}>{{ linkbody }}</a>{% if is_archive_borrow %}
+            <i class="far fa-question-circle"></i>
+        </summary><div>
+            Reading this book on Archive.org may require a free account. <a href="https://help.archive.org/help/borrowing-from-the-lending-library/" target="_blank">Learn more</a>
+        </div></details>{% endif %}</div>
     {% endif %}
     {%- if include.content.drive_links.size > 0 -%}
         {%- for link in include.content.drive_links -%}
@@ -44,4 +52,4 @@
         </div></details></div>
     {%- endif -%}
   </div>
-</div>
+</div>

_sass/nimitta.scss

@@ -540,6 +540,11 @@ h1.overlay-into-banner {
     a {
         font-family: $ui-font-family;
     }
+    .copyright div a {
+        font-family: inherit;
+        text-decoration: underline;
+        color: inherit;
+    }
 }
 
 main header.post-header {
@@ -636,4 +641,4 @@ ol {
             font-size: 14px;
         }
     }
-}
+}

assets/css/content-perma.scss

@@ -162,6 +162,4 @@ div.similar_content_footer {
             padding-bottom: 8px;
         }
     }
-}
-
-
+}