diff --git a/website/public/css/base.css b/website/public/css/base.css
index 846f08d..1ef8492 100644
--- a/website/public/css/base.css
+++ b/website/public/css/base.css
@@ -45,9 +45,11 @@
 
 /** Light theme */
 @media (prefers-color-scheme: light) {
-  --colour-primary-fg: var(--colour-primary-20);
-  --colour-primary-bg: var(--colour-primary-95);
-  --colour-hyperlink: var(--colour-hyperlink-40);
+  :root {
+    --colour-primary-fg: var(--colour-primary-20);
+    --colour-primary-bg: var(--colour-primary-95);
+    --colour-hyperlink: var(--colour-hyperlink-40);
+  }
 }
 
 /** Base typography */