+% the sectsty doesn't look to be maintained but gives, in our case, some warning like:
+% LaTeX Warning: Command \underline has changed.
+% Check if current package is valid.
+% unfortunately had to copy the relevant part
+\newcommand*{\doxypartfont} [1]
+ {\gdef\SS@partnumberfont{\SS@sectid{0}\SS@nopart\SS@makeulinepartchap#1}
+ \gdef\SS@parttitlefont{\SS@sectid{0}\SS@titlepart\SS@makeulinepartchap#1}}
+\newcommand*{\doxychapterfont} [1]
+ {\gdef\SS@chapnumfont{\SS@sectid{1}\SS@nopart\SS@makeulinepartchap#1}
+ \gdef\SS@chaptitlefont{\SS@sectid{1}\SS@titlepart\SS@makeulinepartchap#1}}
+\newcommand*{\doxysectionfont} [1]
+ {\gdef\SS@sectfont{\SS@sectid{2}\SS@rr\SS@makeulinesect#1}}
+\newcommand*{\doxysubsectionfont} [1]
+ {\gdef\SS@subsectfont{\SS@sectid{3}\SS@rr\SS@makeulinesect#1}}
+\newcommand*{\doxysubsubsectionfont} [1]
+ {\gdef\SS@subsubsectfont{\SS@sectid{4}\SS@rr\SS@makeulinesect#1}}
+\newcommand*{\doxyparagraphfont} [1]
+ {\gdef\SS@parafont{\SS@sectid{5}\SS@rr\SS@makeulinesect#1}}
+\newcommand*{\doxysubparagraphfont} [1]
+ {\gdef\SS@subparafont{\SS@sectid{6}\SS@rr\SS@makeulinesect#1}}
+\newcommand*{\doxyminisecfont} [1]
+ {\gdef\SS@minisecfont{\SS@sectid{7}\SS@rr\SS@makeulinepartchap#1}}
+\newcommand*{\doxyallsectionsfont} [1] {\doxypartfont{#1}%
+ \doxychapterfont{#1}%
+ \doxysectionfont{#1}%
+ \doxysubsectionfont{#1}%
+ \doxysubsubsectionfont{#1}%
+ \doxyparagraphfont{#1}%
+ \doxysubparagraphfont{#1}%
+ \doxyminisecfont{#1}}%