diff --git a/doc/source/_static/custom.css b/doc/source/_static/custom.css
new file mode 100644
index 0000000000000000000000000000000000000000..0f4743a58f1d0a25a1bcd284f2ef198780916f9b
--- /dev/null
+++ b/doc/source/_static/custom.css
@@ -0,0 +1,3 @@
+.wy-nav-content {
+    max-width: 65% !important;
+}
\ No newline at end of file
diff --git a/doc/source/conf.py b/doc/source/conf.py
index 6fff24e25b82f153ed1c11352facee97fdee41a4..1db31103990c42246b5539c2c52b8ada8b52025c 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -72,3 +72,7 @@ html_static_path = ['_static']
 
 # -- Copy Button --------------------------------------------------------
 # copybutton_exclude = ['.linenos']
+
+html_css_files = [
+    'custom.css',
+]