diff --git a/docs/doxygen.conf.in b/docs/doxygen.conf.in
index d2f5669..bc87af5 100644
--- a/docs/doxygen.conf.in
+++ b/docs/doxygen.conf.in
@@ -1441,17 +1441,6 @@
 
 FORMULA_FONTSIZE       = 10
 
-# Use the FORMULA_TRANPARENT tag to determine whether or not the images
-# generated for formulas are transparent PNGs. Transparent PNGs are not
-# supported properly for IE 6.0, but are supported on all modern browsers.
-#
-# Note that when changing this option you need to delete any form_*.png files in
-# the HTML output directory before the changes have effect.
-# The default value is: YES.
-# This tag requires that the tag GENERATE_HTML is set to YES.
-
-FORMULA_TRANSPARENT    = YES
-
 # Enable the USE_MATHJAX option to render LaTeX formulas using MathJax (see
 # http://www.mathjax.org) which uses client side Javascript for the rendering
 # instead of using pre-rendered bitmaps. Use this if you do not have LaTeX
diff --git a/docs/requirements.txt b/docs/requirements.txt
new file mode 100644
index 0000000..1348feb
--- /dev/null
+++ b/docs/requirements.txt
@@ -0,0 +1,3 @@
+docutils>=0.20
+sphinx>=7.0.1,<9
+sphinxcontrib-doxylink~=1.13