[PATCH v3 4/4] docs: add support for RTD dark mode

[Mauro Carvalho Chehab <mchehab+huawei@kernel.org>]

This is actually an overlay on the top of the RTD theme, which
requires to include first the RTD theme.

While the CSS overlay file for RTD can be used here, the color
settings can't be applied, as they would do weird things. So,
we need to split the color-dependent logic in order to place it
into a separate file.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---

See [PATCH v3 0/4] at: https://lore.kernel.org/all/cover.1638369365.git.mchehab+huawei@kernel.org/

 Documentation/conf.py                         | 15 +++++++-
 .../sphinx-static/theme_overrides.css         | 16 +-------
 .../sphinx-static/theme_rtd_colors.css        | 37 +++++++++++++++++++
 3 files changed, 53 insertions(+), 15 deletions(-)
 create mode 100644 Documentation/sphinx-static/theme_rtd_colors.css

diff --git a/Documentation/conf.py b/Documentation/conf.py
index d1b6f602b34d..6f4b35bccf3a 100644
--- a/Documentation/conf.py
+++ b/Documentation/conf.py
@@ -215,7 +215,7 @@ html_css_files = []
 if "THEME" in os.environ:
     html_theme = os.environ["THEME"]
 
-if html_theme == 'sphinx_rtd_theme':
+if html_theme == 'sphinx_rtd_theme' or html_theme == 'sphinx_rtd_dark_mode':
     # Read the Docs theme
     try:
         import sphinx_rtd_theme
@@ -227,6 +227,19 @@ if html_theme == 'sphinx_rtd_theme':
         html_css_files = [
             'theme_overrides.css',
         ]
+
+        # Read the Docs dark mode override theme
+        if html_theme == 'sphinx_rtd_dark_mode':
+            try:
+                import sphinx_rtd_dark_mode
+                extensions.append('sphinx_rtd_dark_mode')
+            except ImportError:
+                html_theme == 'sphinx_rtd_theme'
+
+        if html_theme == 'sphinx_rtd_theme':
+                # Add color-specific RTD normal mode
+                html_css_files.append('theme_rtd_colors.css')
+
     except ImportError:
         html_theme = 'classic'
 
diff --git a/Documentation/sphinx-static/theme_overrides.css b/Documentation/sphinx-static/theme_overrides.css
index 459ec5b29d68..f6f2b941a5d6 100644
--- a/Documentation/sphinx-static/theme_overrides.css
+++ b/Documentation/sphinx-static/theme_overrides.css
@@ -1,14 +1,14 @@
 /* -*- coding: utf-8; mode: css -*-
  *
  * Sphinx HTML theme customization: read the doc
- *
+ * Please don't add any color definition here, as the theme should
+ * work for both normal and dark modes.
  */
 
 /* Improve contrast and increase size for easier reading. */
 
 body {
 	font-family: serif;
-	color: black;
 	font-size: 100%;
 }
 
@@ -16,17 +16,8 @@ h1, h2, .rst-content .toctree-wrapper p.caption, h3, h4, h5, h6, legend {
 	font-family: sans-serif;
 }
 
-.wy-menu-vertical li.current a {
-	color: #505050;
-}
-
-.wy-menu-vertical li.on a, .wy-menu-vertical li.current > a {
-	color: #303030;
-}
-
 div[class^="highlight"] pre {
 	font-family: monospace;
-	color: black;
 	font-size: 100%;
 }
 
@@ -104,13 +95,10 @@ div[class^="highlight"] pre {
     /* Menu selection and keystrokes */
 
     span.menuselection {
-	color: blue;
 	font-family: "Courier New", Courier, monospace
     }
 
     code.kbd, code.kbd span {
-	color: white;
-	background-color: darkblue;
 	font-weight: bold;
 	font-family: "Courier New", Courier, monospace
     }
diff --git a/Documentation/sphinx-static/theme_rtd_colors.css b/Documentation/sphinx-static/theme_rtd_colors.css
new file mode 100644
index 000000000000..55b6e1c3664b
--- /dev/null
+++ b/Documentation/sphinx-static/theme_rtd_colors.css
@@ -0,0 +1,37 @@
+/* -*- coding: utf-8; mode: css -*-
+ *
+ * Sphinx HTML theme customization: color settings for RTD (non-dark) theme
+ *
+ */
+
+/* Improve contrast and increase size for easier reading. */
+
+body {
+	color: black;
+}
+
+.wy-menu-vertical li.current a {
+	color: #505050;
+}
+
+.wy-menu-vertical li.on a, .wy-menu-vertical li.current > a {
+	color: #303030;
+}
+
+div[class^="highlight"] pre {
+	color: black;
+}
+
+@media screen {
+
+    /* Menu selection and keystrokes */
+
+    span.menuselection {
+	color: blue;
+    }
+
+    code.kbd, code.kbd span {
+	color: white;
+	background-color: darkblue;
+    }
+}
-- 
2.33.1