diff --git a/book/tex4ebook.cfg b/book/tex4ebook.cfg
index 43adcf5..dffea80 100644
--- a/book/tex4ebook.cfg
+++ b/book/tex4ebook.cfg
@@ -11,4 +11,12 @@
 \Configure{AddCss}{book-ebook.css}
 \Configure{CoverMimeType}{image/jpeg}
 \CoverMetadata{cover/cover-page.jpg}
+\AddToHook{env/tikzpicture/begin}{\fontfamily{opensans-TLF}\selectfont}
+\Configure{@HEAD}{\HCode{
+<style type="text/css">
+  @import url('https://fonts.cdnfonts.com/css/open-sans');
+  body{
+    font-family: 'Open Sans';
+  }
+</style>}}
 \EndPreamble
diff --git a/book/website.cfg b/book/website.cfg
index aa15921..f236b6e 100644
--- a/book/website.cfg
+++ b/book/website.cfg
@@ -9,6 +9,14 @@
 }} 
 
 \Configure{AddCss}{style.css}
+\AddToHook{env/tikzpicture/begin}{\fontfamily{opensans-TLF}\selectfont}
+\Configure{@HEAD}{\HCode{
+<style type="text/css">
+  @import url('https://fonts.cdnfonts.com/css/open-sans');
+  body{
+    font-family: 'Open Sans';
+  }
+</style>}}
 \ConfigureEnv{titlepage}{\ifvmode\IgnorePar\fi\EndP\HCode{<main class="titlepage">}}{\ifvmode\IgnorePar\fi\EndP\HCode{</main>}}{}{}
 
 % Mini TOC