diff --git a/docs/src/css/custom.css b/docs/src/css/custom.css
index 09eae3d..e884f5c 100644
--- a/docs/src/css/custom.css
+++ b/docs/src/css/custom.css
@@ -18,7 +18,7 @@
 }
 
 /* For readability concerns, you should choose a lighter palette in dark mode. */
-[data-theme='dark'] {
+[data-theme="dark"] {
   --ifm-color-primary: #7986cb;
   --ifm-color-primary-dark: #6271c2;
   --ifm-color-primary-darker: #5767be;