diff --git a/src/theorems.dtx b/src/theorems.dtx
index ebe07a3..8160cff 100644
--- a/src/theorems.dtx
+++ b/src/theorems.dtx
@@ -2,12 +2,21 @@
 % On the web, a theorem is emitted as a special |<div>|.
 %    \begin{macrocode}
 %<*htXimera>
+\newcommand{\thmheadlevel}{%
+  \ifnum\value{subsubsection}>0 6%
+  \else\ifnum\value{subsection}>0 5%
+  \else 4%
+  \fi\fi}
 \newcommand{\ConfigureTheoremEnv}[1]{%
 \renewenvironment{#1}[1][]{\refstepcounter{problem}%
 \ifthenelse{\equal{##1}{}}{}{%
-  \HCode{<span class="theorem-like-title">}##1\HCode{</span>}%
+  \HCode{<span class="theorem-like problem-environment">}##1\HCode{</span>}%
 }}{}
-\ConfigureEnv{#1}{\stepcounter{identification}\ifvmode \IgnorePar\fi \EndP\HCode{<div class="theorem-like problem-environment #1" id="problem\arabic{identification}" titletext=" \GetTranslation{#1}">}}{\ifvmode\IgnorePar\fi\EndP\HCode{</div>}\IgnoreIndent}{}{}%
+\ConfigureEnv{#1}
+  {\stepcounter{identification}\ifvmode \IgnorePar\fi \EndP
+   \HCode{<div class="theorem-like problem-environment" id="problem\arabic{identification}"><section>\Hnewline<h\thmheadlevel>}\GetTranslation{#1}\HCode{</h\thmheadlevel>}}
+  {\ifvmode\IgnorePar\fi\EndP\HCode{</section></div>}\IgnoreIndent}
+  {}{}%
 }
 %</htXimera>
 %<classXimera>\theoremstyle{definition} % No italic (because this makes also text in TikZ italic !!!)
diff --git a/ximera.4ht b/ximera.4ht
index be81de1..3423962 100644
--- a/ximera.4ht
+++ b/ximera.4ht
@@ -101,12 +101,21 @@
 \ifdefined\xmNotHintAsExpandable
   \ConfigureQuestionEnv{hint}{hint} % 2024: hint is no longer a 'question-environment'.
 \fi
+\newcommand{\thmheadlevel}{%
+  \ifnum\value{subsubsection}>0 6%
+  \else\ifnum\value{subsection}>0 5%
+  \else 4%
+  \fi\fi}
 \newcommand{\ConfigureTheoremEnv}[1]{%
 \renewenvironment{#1}[1][]{\refstepcounter{problem}%
 \ifthenelse{\equal{##1}{}}{}{%
-  \HCode{<span class="theorem-like-title">}##1\HCode{</span>}%
+  \HCode{<span class="theorem-like-problem-environment">}##1\HCode{</span>}%
 }}{}
-\ConfigureEnv{#1}{\stepcounter{identification}\ifvmode \IgnorePar\fi \EndP\HCode{<div class="theorem-like problem-environment #1" id="problem\arabic{identification}" titletext=" \GetTranslation{#1}">}}{\ifvmode\IgnorePar\fi\EndP\HCode{</div>}\IgnoreIndent}{}{}%
+\ConfigureEnv{#1}
+  {\stepcounter{identification}\ifvmode \IgnorePar\fi \EndP
+   \HCode{<div class="theorem-like-problem-environment" id="problem\arabic{identification}"><section>\Hnewline<h\thmheadlevel>}\GetTranslation{#1}\HCode{</h\thmheadlevel>}}
+  {\ifvmode\IgnorePar\fi\EndP\HCode{</section></div>}\IgnoreIndent}
+  {}{}%
 }
 
 
diff --git a/ximera.pdf b/ximera.pdf
index ef81ca4..4066d0c 100644
Binary files a/ximera.pdf and b/ximera.pdf differ