adjusted docs

Author: seanpue

doc/source/_static/custom.css

@@ -0,0 +1,7 @@
+/*
+Custom CSS for stderr stream output.
+*/
+
+.stderr {
+    background-color: #FCC;
+}

doc/source/conf.py

@@ -41,3 +41,4 @@
         "repo": "jupyter/jupyter-sphinx",
     },
 }
+html_static_path = ["_static/custom.css"]  # css overrides for Alabaster theme

doc/source/index.rst

@@ -251,10 +251,13 @@ produces:
 
     print("hello, world!", file=sys.stderr)
 
-.. warning::
+.. note::
+  To `adjust the CSS <https://docs.readthedocs.io/en/stable/guides/adding-custom-css.html>`_
+  of the ``stderr`` stream, use the ``stderr`` class. If you are using the default
+  Sphinx theme, for example, add the following
+  `custom CSS <https://alabaster.readthedocs.io/en/latest/customization.html#custom-stylesheet>`_:
+    ``.stderr {background-color: #FCC}``.
 
-    Note that output written to ``stderr`` is not displayed any differently than output written
-    to ``stdout``.
 
 Controlling the execution environment
 -------------------------------------