Add compatibility for sphinx4

Sphinx 4.x moves javascript and css declarations to `script_files` and `css_files`. This patch fixes duplicatd link and script tags when using sphinx4

Sphinx 4.x changes the default setting of html_codeblock_linenos_style to 'inline' and deprecates `html_codeblock_linenos_style`. The css for `.hll` to make the hightling span the full line cause the line number and code to be split on seperate lines. I could not get the highlight to span the full line so it was removed completely. I also made line numbers not selectible by the user.

This changes also adds the needed changes to the tox testing enviorment alhough, sphinx4 is not officially released to pypi yet. You will need to test these changes locally using: `pip install git+https://github.com/sphinx-doc/sphinx@master`

.circleci/config.yml

@@ -8,7 +8,7 @@ commands:
         type: string
       sphinx-version:
         type: string
-        default: "16,17,18,20,21,22,23,24,30,31,32,33,34,latest"
+        default: "16,17,18,20,21,22,23,24,30,31,32,33,34,35,40,latest"
     steps:
       - checkout
       - run: pip install --user tox

sphinx_rtd_theme/layout.html

@@ -20,8 +20,10 @@
   {%- endblock -%}
 
   {#- CSS #}
-  <link rel="stylesheet" href="{{ pathto('_static/' + style, 1) }}" type="text/css" />
+  {%- if (sphinx_version <= "4.0.0") -%}
-  <link rel="stylesheet" href="{{ pathto('_static/pygments.css', 1) }}" type="text/css" />
+    <link rel="stylesheet" href="{{ pathto('_static/' + style, 1) }}" type="text/css" />
+    <link rel="stylesheet" href="{{ pathto('_static/pygments.css', 1) }}" type="text/css" />
+  {%- endif %}
   {%- for css in css_files %}
     {%- if css|attr("rel") %}
       <link rel="{{ css.rel }}" href="{{ pathto(css.filename, 1) }}" type="text/css"{% if css.title is not none %} title="{{ css.title }}"{% endif %} />
@@ -57,7 +59,9 @@
   {%- if not embedded %}
   {# XXX Sphinx 1.8.0 made this an external js-file, quick fix until we refactor the template to inherert more blocks directly from sphinx #}
     {%- if sphinx_version >= "1.8.0" -%}
+      {%- if sphinx_version <= "4.0.0" -%}
       <script type="text/javascript" id="documentation_options" data-url_root="{{ url_root }}" src="{{ pathto('_static/documentation_options.js', 1) }}"></script>
+      {%- endif -%}
       {%- for scriptfile in script_files %}
         {{ js_tag(scriptfile) }}
       {%- endfor %}

src/sass/_theme_rst.sass

@@ -85,18 +85,13 @@
     padding: ($base-line-height / 2) ($base-line-height / 2)
     display: block
     overflow: auto
-    & .hll
-      // Line emphasis spans full width
-      display: block
-      margin: 0 (-1 * $base-line-height / 2)
-      padding: 0 ($base-line-height / 2)
   pre.literal-block, div[class^='highlight'] pre, .linenodiv pre
     font-family: $code-font-family
     font-size: 12px
     line-height: 1.4
   
-  // Do not allow selection of code block prompts
+  // Do not allow selection of code block prompts and line numbers
-  div.highlight .gp 
+  .lineno, .gp 
     user-select: none
     pointer-events: none
 

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py{27,36,37,38,39}-sphinx{16,17,18,20,21,22,23,24,30,31,32,33,34,latest}
+envlist = py{27,36,37,38,39}-sphinx{16,17,18,20,21,22,23,24,30,31,32,33,34,35,40,latest}
 
 [testenv]
 setev =
@@ -22,6 +22,8 @@ deps =
     sphinx32: Sphinx < 3.3
     sphinx33: Sphinx < 3.4
     sphinx34: Sphinx < 3.5
+    sphinx35: Sphinx < 4.0
+    sphinx40: Sphinx < 4.1
     sphinxlatest: Sphinx
 commands =
     pytest {posargs} tests/