diff --git a/swad_browser.c b/swad_browser.c
index 7399d39c5..1ea6474b1 100644
--- a/swad_browser.c
+++ b/swad_browser.c
@@ -4477,7 +4477,7 @@ static void Brw_PutIconToExpandFolder (const char *FileBrowserId,const char *Row
    switch (HiddenOrVisible)
      {
       case HidVis_HIDDEN:
-	 HTM_DIV_Begin ("id=\"expand_%s_%s\" class=\"NOT_SHOWN\"",
+	 HTM_DIV_Begin ("id=\"expand_%s_%s\" style=\"display:none;\"",
 			FileBrowserId,RowId);
 	 break;
       case HidVis_VISIBLE:
@@ -4515,8 +4515,7 @@ static void Brw_PutIconToContractFolder (const char *FileBrowserId,const char *R
    switch (HiddenOrVisible)
      {
       case HidVis_HIDDEN:
-	 HTM_DIV_Begin ("id=\"contract_%s_%s\" class=\"NOT_SHOWN\"",
-	 // HTM_DIV_Begin ("id=\"contract_%s_%s\" style=\"display:none;\"",
+	 HTM_DIV_Begin ("id=\"contract_%s_%s\" style=\"display:none;\"",
 			FileBrowserId,RowId);
 	 break;
       case HidVis_VISIBLE:
@@ -4686,14 +4685,15 @@ static void Brw_PutIconFolderWithoutPlus (const char *FileBrowserId,const char *
 			                  bool Open,HidVis_HiddenOrVisible_t HiddenOrVisible)
   {
    extern const char *Txt_Folder;
-   extern const char *HidVis_ShownClass[HidVis_NUM_HIDDEN_VISIBLE];
+   extern const char *HidVis_ShownStyle[HidVis_NUM_HIDDEN_VISIBLE];
 
    /***** Begin container *****/
-   HTM_DIV_Begin ("id=\"folder_%s_%s_%s\" class=\"%s%s\"",
+   HTM_DIV_Begin ("id=\"folder_%s_%s_%s\" class=\"%s\"%s",
 		  Open ? "open" :
 			 "closed",
 		  FileBrowserId,RowId,
-                  The_GetColorRows (),HidVis_ShownClass[HiddenOrVisible]);
+                  The_GetColorRows (),
+		  HidVis_ShownStyle[HiddenOrVisible]);
 
       /***** Icon *****/
       Ico_PutIcon (Open ? "folder-open-yellow.png" :
@@ -4712,14 +4712,15 @@ static void Brw_PutIconFolderWithoutPlus (const char *FileBrowserId,const char *
 static void Brw_PutIconFolderWithPlus (const char *FileBrowserId,const char *RowId,
 				       bool Open,HidVis_HiddenOrVisible_t HiddenOrVisible)
   {
-   extern const char *HidVis_ShownClass[HidVis_NUM_HIDDEN_VISIBLE];
+   extern const char *HidVis_ShownStyle[HidVis_NUM_HIDDEN_VISIBLE];
 
    /***** Begin container *****/
-   HTM_DIV_Begin ("id=\"folder_%s_%s_%s\" class=\"%s%s\"",
+   HTM_DIV_Begin ("id=\"folder_%s_%s_%s\" class=\"%s\"%s",
 		  Open ? "open" :
 			 "closed",
 		  FileBrowserId,RowId,
-		  The_GetColorRows (),HidVis_ShownClass[HiddenOrVisible]);
+		  The_GetColorRows (),
+		  HidVis_ShownStyle[HiddenOrVisible]);
 
       /***** Form and icon *****/
       Ico_PutContextualIconToCreateInFolder (Brw_ActFormCreate[Gbl.FileBrowser.Type],
diff --git a/swad_changelog.h b/swad_changelog.h
index a047633a6..448431ea6 100644
--- a/swad_changelog.h
+++ b/swad_changelog.h
@@ -632,10 +632,11 @@ TODO: Francisco Javier Fern
 Me sale este error, no sé si por no recordar yo la sintaxis apropiada para mandar a varios destinatarios. ¿No era así?
 "can npt create received message (duplicated entry '243218-2160773' for key 'UsrCod_MsgCod')
 */
-#define Log_PLATFORM_VERSION	"SWAD 23.13 (2023-09-20)"
+#define Log_PLATFORM_VERSION	"SWAD 23.13.1 (2023-09-20)"
 #define CSS_FILE		"swad22.120.4.css"
 #define JS_FILE			"swad22.49.js"
 /*
+	Version 23.13.1:  Sep 20, 2023  Fixed bug in browser. Reported by Eva Martínez Ortigosa. (336953 lines)
 	Version 23.13:	  Sep 20, 2023  Code refactoring in hierarchy and cache. (336951 lines)
 	Version 23.12:	  Sep 20, 2023  Code refactoring in hierarchy and cache. (336919 lines)
 	Version 23.11:	  Sep 20, 2023  Code refactoring in hierarchy. (337184 lines)