address docs accessibility issues (#3205)

fix color contrast
add back link underlining

Author: zingale

Docs/source/_static/theme_overrides.css

@@ -34,7 +34,7 @@ div#example-notebook div.highlight-default div.highlight {
 
 .wy-side-nav-search>div.branch{
     font-weight:normal;
-    color:rgba(255,255,255,0.3);
+    color:rgba(255,255,255);
     font-size:100%;
     display:inline-block;
     padding:4px 6px;
@@ -47,4 +47,25 @@ div#example-notebook div.highlight-default div.highlight {
     margin-bottom:.809em; */
     color:#fcfcfc;
     font-weight:bold;
-}
+}
+
+/* Underline links everywhere */
+.wy-nav-content a {
+    text-decoration: underline;
+    text-decoration-style: dotted;
+    text-underline-offset: 0.15em;
+}
+
+/* Left sidebar navigation links */
+.wy-menu a {
+    text-decoration-line: underline;
+    text-decoration-style: dotted;
+    text-underline-offset: 0.15em;
+}
+
+.wy-side-nav-search a {
+    text-decoration-line: underline;
+    text-decoration-style: dotted;
+    text-underline-offset: 0.15em;
+}
+

Docs/source/conf.py

@@ -60,6 +60,7 @@ def get_version():
               'sphinx_copybutton',
               'sphinx_prompt',
               'breathe',
+              'sphinx_rtd_theme_ext_color_contrast',
               'IPython.sphinxext.ipython_console_highlighting']
 
 # bibtex

requirements.txt

@@ -13,3 +13,6 @@ sphinx-prompt
 codespell
 sphinx-math-dollar
 sphinx-copybutton
+
+# for accessibility
+sphinx-rtd-theme-ext-color-contrast