Use sphinx_rtd_theme instead of our lightly-customized version of sph…

…inx default.

The main benefit of this change is the responsive layout for phones and
tablets.

docs/Makefile

@@ -1,3 +1,6 @@
+.PHONY: all
+all: sphinx
+
 SPHINXOPTS=-n -W -d build/doctrees .
 
 .PHONY: sphinx

docs/conf.py

@@ -75,32 +75,6 @@
     "multi_future",
 ]
 
-html_static_path = ['tornado.css']
-html_theme = 'default'
-html_style = "tornado.css"
-highlight_language = "none"
-html_theme_options = dict(
-    footerbgcolor="#fff",
-    footertextcolor="#000",
-    sidebarbgcolor="#fff",
-    #sidebarbtncolor
-    sidebartextcolor="#4d8cbf",
-    sidebarlinkcolor="#216093",
-    relbarbgcolor="#fff",
-    relbartextcolor="#000",
-    relbarlinkcolor="#216093",
-    bgcolor="#fff",
-    textcolor="#000",
-    linkcolor="#216093",
-    visitedlinkcolor="#216093",
-    headbgcolor="#fff",
-    headtextcolor="#4d8cbf",
-    codebgcolor="#fff",
-    codetextcolor="#060",
-    bodyfont="Georgia, serif",
-    headfont="Calibri, sans-serif",
-    stickysidebar=True,
-    )
 html_favicon = 'favicon.ico'
 
 latex_documents = [
@@ -123,3 +97,13 @@
 intersphinx_mapping = {
     'python': ('http://python.readthedocs.org/en/latest/', None),
     }
+
+on_rtd = os.environ.get('READTHEDOCS', None) == 'True'
+
+# On RTD we can't import sphinx_rtd_theme, but it will be applied by
+# default anyway.  This block will use the same theme when building locally
+# as on RTD.
+if not on_rtd:
+    import sphinx_rtd_theme
+    html_theme = 'sphinx_rtd_theme'
+    html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]

maint/requirements.txt

@@ -21,6 +21,7 @@ autopep8==1.0.2
 coverage==3.7.1
 pep8==1.5.6
 pyflakes==0.8.1
+sphinx-rtd-theme==0.1.6
 tox==1.7.1
 virtualenv==1.11.6