Support dark mode in the documentation (#6653)

docs/_static/custom.css

@@ -7,4 +7,50 @@
 }
 .rst-content dl p + ol, .rst-content dl p + ul {
     margin-top: -6px; /* Compensates margin-top: 12px of p  */
-}
+}
+
+/*override some styles in
+sphinx-rtd-dark-mode/static/dark_mode_css/general.css*/
+.theme-switcher {
+    right: 0.4em !important;
+    top: 0.6em !important;
+    -webkit-box-shadow: 0px 3px 14px 4px rgba(0, 0, 0, 0.30) !important;
+    box-shadow: 0px 3px 14px 4px rgba(0, 0, 0, 0.30) !important;
+    height: 2em !important;
+    width: 2em !important;
+}
+
+/*place the toggle button for dark mode
+at the bottom right corner on small screens*/
+@media (max-width: 768px) {
+    .theme-switcher {
+        right: 0.4em !important;
+        bottom: 2.6em !important;
+        top: auto !important;
+    }
+}
+
+/*persist blue color at the top left used in
+default rtd theme*/
+html[data-theme="dark"] .wy-side-nav-search,
+html[data-theme="dark"] .wy-nav-top {
+    background-color: #1d577d !important;
+}
+
+/*all the styles below used to present
+API objects nicely in dark mode*/
+html[data-theme="dark"] .sig.sig-object {
+    border-left-color: #3e4446 !important;
+    background-color: #202325 !important
+}
+
+html[data-theme="dark"] .sig-name,
+html[data-theme="dark"] .sig-prename,
+html[data-theme="dark"] .property,
+html[data-theme="dark"] .sig-param,
+html[data-theme="dark"] .sig-paren,
+html[data-theme="dark"] .sig-return-icon,
+html[data-theme="dark"] .sig-return-typehint,
+html[data-theme="dark"] .optional {
+    color: #e8e6e3 !important
+}

docs/conf.py

@@ -35,6 +35,7 @@ extensions = [
     "sphinx.ext.coverage",
     "sphinx.ext.intersphinx",
     "sphinx.ext.viewcode",
+    "sphinx_rtd_dark_mode",
 ]
 
 templates_path = ["_templates"]
@@ -174,3 +175,5 @@ hoverxref_role_types = {
     "signal": "tooltip",
 }
 hoverxref_roles = ["command", "reqmeta", "setting", "signal"]
+
+default_dark_mode = False

docs/requirements.txt

@@ -2,3 +2,4 @@ sphinx==8.1.3
 sphinx-hoverxref==1.4.2
 sphinx-notfound-page==1.0.4
 sphinx-rtd-theme==3.0.2
+sphinx-rtd-dark-mode==1.3.0