diff --git a/book/sourdough.sty b/book/sourdough.sty
index fe2f1ca..d38a7cd 100644
--- a/book/sourdough.sty
+++ b/book/sourdough.sty
@@ -52,8 +52,9 @@
 \DeclareRobustCommand\sbseries{\fontseries{sb}\selectfont}
 % Fonts for accessibility
 \ifdefined\isaccessible
-    \setmainfont{Open Sans}[
-    Scale=MatchLowercase]
+    \usepackage[mathrm=sym]{unicode-math}
+    \setmathfont{Fira Math}[Scale=MatchLowercase]
+    \setmainfont{Open Sans}[Scale=MatchLowercase]
 \else
     \setmainfont{TeX Gyre Pagella}[Scale=1.0] % Or Palatino Linotype, etc.
     % TODO not available on github CI
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