diff --git a/lang/sl.css b/lang/sl.css
new file mode 100644
index 0000000..1389c13
--- /dev/null
+++ b/lang/sl.css
@@ -0,0 +1,4 @@
+:lang(sl) .theorem::before { content: 'Izrek ' counter(theorem) '. ' !important; }
+:lang(sl) .lemma::before { content: 'Lema ' counter(theorem) '. ' !important; }
+:lang(sl) .proof::before { content: 'Dokaz. ' attr(title) !important; }
+:lang(sl) .definition::before { content: 'Definicija ' counter(definition) '. ' !important; }
diff --git a/languages.html b/languages.html
index 1ef2c1b..cf1c579 100644
--- a/languages.html
+++ b/languages.html
@@ -50,6 +50,7 @@
       <option value="mwl">Mirandese (mwl)</option>
       <option value="pt">Portuguese (pt)</option>
       <option value="ro">Romanian (ro)</option>
+      <option value="sl">Slovenian (sl)</option>
       <option value="tr">Turkish (tr)</option>
       <option value="zh-hans">Simplified Chinese (zh-hans)</option>
       <option value="zh-hant">Traditional Chinese (zh-hant)</option>