diff --git a/_layouts/default.html b/_layouts/default.html
index 704bebae5..d575d3e1a 100644
--- a/_layouts/default.html
+++ b/_layouts/default.html
@@ -11,7 +11,7 @@ layout: compress
 <!-- `site.alt_lang` can specify a language different from the UI -->
 <html
   lang="{{ page.lang | default: site.alt_lang | default: site.lang }}"
-  {%- if site.theme_mode == 'light' or site.theme_mode == 'dark' -%}
+  {% if site.theme_mode == 'light' or site.theme_mode == 'dark' -%}
     data-bs-theme="{{ site.theme_mode }}"
   {%- endif -%}
 >
