Docs: css tweaks

* Add vertical space between items in "open" lists
  (rtfd/sphinx_rtd_theme#590)
* Distinguish shell prompts in console examples,
  and omit them if the code is copied
* Add css and js extras directly from Sphinx conf.py
  (no need to override template)

docs/_static/anymail-theme.css

@@ -0,0 +1,21 @@
+/* Anymail modifications to sphinx-rtd-theme styles */
+
+/* List item spacing: https://github.com/rtfd/sphinx_rtd_theme/issues/590 */
+.rst-content .section ol li p:last-child,
+.rst-content .section ul li p:last-child {
+    margin-bottom: 24px;
+}
+
+
+/* Pygments shell/console prompt: */
+.highlight .gp {
+    /* The RTD theme shows prompts the same color as other code.
+       We want to distinguish them (like most Pygments themes do). */
+    color: #d14;
+
+    /* Exclude prompt characters when copying from highlighted code. */
+    user-select: none;
+    -moz-user-select: none;
+    -webkit-user-select: none;
+    -ms-user-select: none;
+}