set max width to 65%

doc/source/_static/custom.css

+.wy-nav-content {
+    max-width: 65% !important;
+}
\ No newline at end of file

doc/source/conf.py

@@ -72,3 +72,7 @@ html_static_path = ['_static']
 
 # -- Copy Button --------------------------------------------------------
 # copybutton_exclude = ['.linenos']
+
+html_css_files = [
+    'custom.css',
+]