diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 3163e056a559913bf55d32c6485ca35e52c3f95f..ef81e7db0abd2bd3e208173803739eee62897c8d 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -51,7 +51,7 @@ pages:
                -o ${TARGET} ../slides/${MDFILE} \
                -V revealjs-url=https://unpkg.com/reveal.js/ \
                -V theme=${REVEAL_THEME} \
-               --css=../slides/dumux_course.css
+               --include-in-header=../slides/dumux_course_header.html
       done
     cd ..
   - mkdir public && mv build/* public && cp -r slides/img public
diff --git a/slides/dumux_course.css b/slides/dumux_course_header.html
similarity index 97%
rename from slides/dumux_course.css
rename to slides/dumux_course_header.html
index 8a8f0f73f557e78440acca86ca1b7b11f4fb6848..57d4146013914b426dc582bd9931650e817b3404 100644
--- a/slides/dumux_course.css
+++ b/slides/dumux_course_header.html
@@ -1,3 +1,4 @@
+<style>
 @import url("https://fonts.googleapis.com/css?family=Nanum+Gothic");
 
 :root {
@@ -45,3 +46,4 @@
     font-size: 1.75em;
     font-family: var(--font-family), sans-serif;
 }
+</style>