diff --git a/swad_HTML.c b/swad_HTML.c
index 1f3ec504..465dd09a 100644
--- a/swad_HTML.c
+++ b/swad_HTML.c
@@ -69,6 +69,7 @@ static unsigned HTM_DD_NestingLevel       = 0;
 static unsigned HTM_A_NestingLevel        = 0;
 static unsigned HTM_SCRIPT_NestingLevel   = 0;
 static unsigned HTM_LABEL_NestingLevel    = 0;
+static unsigned HTM_BUTTON_NestingLevel   = 0;
 static unsigned HTM_TEXTAREA_NestingLevel = 0;
 static unsigned HTM_SELECT_NestingLevel   = 0;
 
@@ -1215,6 +1216,27 @@ void HTM_INPUT_CHECKBOX (const char *Name,bool SubmitOnChange,
    fprintf (Gbl.F.Out," />");
   }
 
+/*****************************************************************************/
+/********************************** Buttons **********************************/
+/*****************************************************************************/
+
+void HTM_BUTTON_Begin (const char *Class)
+  {
+   fprintf (Gbl.F.Out,"<button type=\"submit\" class=\"%s\">",Class);
+
+   HTM_BUTTON_NestingLevel++;
+  }
+
+void HTM_BUTTON_End (void)
+  {
+   if (HTM_BUTTON_NestingLevel == 0)	// No BUTTON open
+      Ale_ShowAlert (Ale_ERROR,"Trying to close unopened BUTTON.");
+
+   fprintf (Gbl.F.Out,"</button>");
+
+   HTM_BUTTON_NestingLevel--;
+  }
+
 /*****************************************************************************/
 /********************************* Text areas ********************************/
 /*****************************************************************************/
diff --git a/swad_HTML.h b/swad_HTML.h
index d791fdef..ba2af2a4 100644
--- a/swad_HTML.h
+++ b/swad_HTML.h
@@ -127,6 +127,9 @@ void HTM_INPUT_RADIO (const char *Name,bool SubmitOnClick,
 void HTM_INPUT_CHECKBOX (const char *Name,bool SubmitOnChange,
 		         const char *fmt,...);
 
+void HTM_BUTTON_Begin (const char *Class);
+void HTM_BUTTON_End (void);
+
 void HTM_TEXTAREA_Begin (const char *fmt,...);
 void HTM_TEXTAREA_End (void);
 
diff --git a/swad_button.c b/swad_button.c
index f7a023a3..f17ecb36 100644
--- a/swad_button.c
+++ b/swad_button.c
@@ -100,53 +100,47 @@ void Btn_PutButtonInline (Btn_Button_t Button,const char *TxtButton)
 void Btn_PutCreateButton (const char *TxtButton)
   {
    HTM_DIV_Begin ("class=\"CM\"");
-   fprintf (Gbl.F.Out,"<button type=\"submit\" class=\"BT_SUBMIT BT_CREATE\">"
-                      "%s"
-                      "</button>",
-            TxtButton);
+   HTM_BUTTON_Begin ("BT_SUBMIT BT_CREATE");
+   fprintf (Gbl.F.Out,"%s",TxtButton);
+   HTM_BUTTON_End ();
    HTM_DIV_End ();
   }
 
 void Btn_PutCreateButtonInline (const char *TxtButton)
   {
-   fprintf (Gbl.F.Out,"<button type=\"submit\" class=\"BT_SUBMIT_INLINE BT_CREATE\">"
-                      "%s"
-                      "</button>",
-            TxtButton);
+   HTM_BUTTON_Begin ("BT_SUBMIT_INLINE BT_CREATE");
+   fprintf (Gbl.F.Out,"%s",TxtButton);
+   HTM_BUTTON_End ();
   }
 
 void Btn_PutConfirmButton (const char *TxtButton)
   {
    HTM_DIV_Begin ("class=\"CM\"");
-   fprintf (Gbl.F.Out,"<button type=\"submit\" class=\"BT_SUBMIT BT_CONFIRM\">"
-                      "%s"
-                      "</button>",
-            TxtButton);
+   HTM_BUTTON_Begin ("BT_SUBMIT BT_CONFIRM");
+   fprintf (Gbl.F.Out,"%s",TxtButton);
+   HTM_BUTTON_End ();
    HTM_DIV_End ();
   }
 
 void Btn_PutConfirmButtonInline (const char *TxtButton)
   {
-   fprintf (Gbl.F.Out,"<button type=\"submit\" class=\"BT_SUBMIT_INLINE BT_CONFIRM\">"
-                      "%s"
-                      "</button>",
-            TxtButton);
+   HTM_BUTTON_Begin ("BT_SUBMIT_INLINE BT_CONFIRM");
+   fprintf (Gbl.F.Out,"%s",TxtButton);
+   HTM_BUTTON_End ();
   }
 
 void Btn_PutRemoveButton (const char *TxtButton)
   {
    HTM_DIV_Begin ("class=\"CM\"");
-   fprintf (Gbl.F.Out,"<button type=\"submit\" class=\"BT_SUBMIT BT_REMOVE\">"
-                      "%s"
-                      "</button>",
-            TxtButton);
+   HTM_BUTTON_Begin ("BT_SUBMIT BT_REMOVE");
+   fprintf (Gbl.F.Out,"%s",TxtButton);
+   HTM_BUTTON_End ();
    HTM_DIV_End ();
   }
 
 void Btn_PutRemoveButtonInline (const char *TxtButton)
   {
-   fprintf (Gbl.F.Out,"<button type=\"submit\" class=\"BT_SUBMIT_INLINE BT_REMOVE\">"
-                      "%s"
-                      "</button>",
-            TxtButton);
+   HTM_BUTTON_Begin ("BT_SUBMIT_INLINE BT_REMOVE");
+   fprintf (Gbl.F.Out,"%s",TxtButton);
+   HTM_BUTTON_End ();
   }
diff --git a/swad_changelog.h b/swad_changelog.h
index e7e4d51d..a9a5d986 100644
--- a/swad_changelog.h
+++ b/swad_changelog.h
@@ -487,7 +487,7 @@ enscript -2 --landscape --color --file-align=2 --highlight --line-numbers -o - *
 En OpenSWAD:
 ps2pdf source.ps destination.pdf
 */
-#define Log_PLATFORM_VERSION	"SWAD 19.57 (2019-11-09)"
+#define Log_PLATFORM_VERSION	"SWAD 19.58 (2019-11-09)"
 #define CSS_FILE		"swad19.47.css"
 #define JS_FILE			"swad19.39.js"
 /*
@@ -495,6 +495,7 @@ ps2pdf source.ps destination.pdf
 // TODO: Impedir la creación y edición de proyectos si no son editables.
 // TODO: Importante: filtrar proyectos por usuarios (igual que en trabajos o en asistencia)
 
+	Version 19.58:    Nov 09, 2019	Code refactoring in HTML definition lists. (246169 lines)
 	Version 19.57:    Nov 09, 2019	Code refactoring in HTML definition lists. (246156 lines)
 	Version 19.56:    Nov 08, 2019	Fixed bug in groups.
 					New constants for sizes of numerical strings. (246104 lines)