[fix] sphinx 3.1 CSS issues

See sphinx-doc project, PR 7838 & 7484 with elementary patch to the basic CSS:

- https://github.com/sphinx-doc/sphinx/issues/7838#issuecomment-646009605
- https://github.com/sphinx-doc/sphinx/pull/7484#issuecomment-646058972

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

docs/_themes/searx/static/searx.css

@@ -138,3 +138,32 @@ caption {
   caption-side: top;
   text-align: left;
 }
+
+/* bugs since sphinx 3.1
+
+See sphinx-doc project, PR 7838 & 7484 with elementary patch to the basic CSS:
+
+- https://github.com/sphinx-doc/sphinx/issues/7838#issuecomment-646009605
+- https://github.com/sphinx-doc/sphinx/pull/7484#issuecomment-646058972
+
+*/
+
+li > p:first-child {
+    margin-top: 0;
+}
+
+li > p:last-child {
+    margin-bottom: 0;
+}
+
+div.admonition dl {
+    margin-bottom: 0;
+}
+
+div.sidebar {
+    clear: none;
+}
+
+div.admonition, div.topic, pre {
+    clear: none;
+}