diff --git a/css/swad15.51.3.css b/css/swad15.52.css
similarity index 97%
rename from css/swad15.51.3.css
rename to css/swad15.52.css
index d95a63bf..77ac34c4 100644
--- a/css/swad15.51.3.css
+++ b/css/swad15.52.css
@@ -1560,14 +1560,27 @@ a:hover img.CENTRE_PHOTO_SHOW
 .TEST_EDI		{color:#404040; font-size:12pt;}
 .TEST_EDI_LIGHT		{color:#A0A0A0; font-size:12pt;}
 
-.HOR			{font-family:"Arial Narrow","Nimbus Sans L","DejaVu LGC Sans Condensed",sans-serif; color:#345C6C; font-size:10pt; line-height:110%; letter-spacing:0;}
-.FREE0			{background-color:#F4F2EA; border:solid 1px; border-color:#F4F2EA #E0D9C2 #EEEADC #F4F2EA;}
-.FREE1			{background-color:#F4F2EA; border:solid 1px; border-color:#F4F2EA #E0D9C2 #E0D9C2 #F4F2EA;}
-.FREE2			{background-color:#FBFAF7; border:solid 1px; border-color:#FBFAF7 #E0D9C2 #F5F2E9 #FBFAF7;}
-.FREE3			{background-color:#FBFAF7; border:solid 1px; border-color:#FBFAF7 #E0D9C2 #E0D9C2 #FBFAF7;}
-.THEO			{background-color:#C0DAE4; border:solid 2px; border-color:#C9E3ED #B5CFD9 #B5CFD9 #C9E3ED;}
-.PRAC			{background-color:#DBE5E9; border:solid 2px; border-color:#E4EEF2 #D0DADE #D0DADE #E4EEF2;}
-.TUTO			{background-color:#D6E9C3; border:solid 2px; border-color:#DFEEE0 #CAE3B1 #CAE3B1 #DFEEE0;}
+/******************************* Time table **********************************/
+#timetable
+	{
+	width:100%;
+	margin:0 auto;
+	}
+.TT_TXT
+	{
+	font-family:"Arial Narrow","Nimbus Sans L","DejaVu LGC Sans Condensed",sans-serif;
+	color:#345C6C;
+	font-size:10pt;
+	line-height:110%;
+	letter-spacing:0;
+	}
+.FREE0	{height:20px; background-color:#F4F2EA; border:solid 1px; border-color:#F4F2EA #E0D9C2 #EEEADC #F4F2EA;}
+.FREE1	{height:20px; background-color:#F4F2EA; border:solid 1px; border-color:#F4F2EA #E0D9C2 #E0D9C2 #F4F2EA;}
+.FREE2	{height:20px; background-color:#FBFAF7; border:solid 1px; border-color:#FBFAF7 #E0D9C2 #F5F2E9 #FBFAF7;}
+.FREE3	{height:20px; background-color:#FBFAF7; border:solid 1px; border-color:#FBFAF7 #E0D9C2 #E0D9C2 #FBFAF7;}
+.THEO	{height:20px; background-color:#C0DAE4; border:solid 2px; border-color:#C9E3ED #B5CFD9 #B5CFD9 #C9E3ED;}
+.PRAC	{height:20px; background-color:#DBE5E9; border:solid 2px; border-color:#E4EEF2 #D0DADE #D0DADE #E4EEF2;}
+.TUTO	{height:20px; background-color:#D6E9C3; border:solid 2px; border-color:#DFEEE0 #CAE3B1 #CAE3B1 #DFEEE0;}
 
 .PREF_OFF
 	{
@@ -1756,7 +1769,7 @@ a:hover img.CENTRE_PHOTO_SHOW
 	box-sizing:border-box;
 	min-width:312px;
 	}
-	              
+
 /********************************** Page foot ********************************/
 @media only screen and (max-width: 899px)
 	{	/* For mobile-phones */
diff --git a/sql/cambios.sql b/sql/cambios.sql
index e90b25e9..78c33992 100644
--- a/sql/cambios.sql
+++ b/sql/cambios.sql
@@ -11166,3 +11166,17 @@ SELECT * FROM expanded_folders WHERE ClickTime<FROM_UNIXTIME(UNIX_TIMESTAMP()-'1
 
 -----
 SELECT UsrCod,'Y',Sex FROM usr_data WHERE UsrCod IN (SELECT DISTINCT UsrCod FROM admin WHERE Scope='Sys' UNION SELECT DISTINCT admin.UsrCod FROM admin,institutions WHERE admin.Scope='Ins' AND admin.Cod=institutions.InsCod AND institutions.CtyCod='724') AS admin_codes ORDER BY Surname1,Surname2,FirstName,UsrCod;
+
+
+
+-----------------------
+
+CREATE TABLE timetable_crs_backup LIKE timetable_crs;
+INSERT INTO timetable_crs_backup SELECT * FROM timetable_crs;
+
+CREATE TABLE timetable_tut_backup LIKE timetable_tut;
+INSERT INTO timetable_tut_backup SELECT * FROM timetable_tut;
+
+UPDATE timetable_crs SET Hour=Hour+2;
+UPDATE timetable_tut SET Hour=Hour+2;
+
diff --git a/swad_changelog.h b/swad_changelog.h
index fee2ed2b..f5e93dce 100644
--- a/swad_changelog.h
+++ b/swad_changelog.h
@@ -111,18 +111,19 @@
 // TODO: Edition of courses: Rename "Curso" to "Aņo / semestre / cuatrimestre"
 // TODO: Listing of courses: Put "Optativas" year at the end
 // TODO: Timetable: Sunday can be the first day of the week
-// TODO: Timetable: Day can start at 6 am
 
 /*****************************************************************************/
 /****************************** Public constants *****************************/
 /*****************************************************************************/
 
-#define Log_PLATFORM_VERSION	"SWAD 15.51.4 (2015/11/30)"
-#define CSS_FILE		"swad15.51.4.css"
+#define Log_PLATFORM_VERSION	"SWAD 15.52 (2015/11/30)"
+#define CSS_FILE		"swad15.52.css"
 
 // Number of lines (includes comments but not blank lines) has been got with the following command:
 // nl swad*.c swad*.h css/swad*.css py/swad*.py js/swad*.js soap/swad*.h sql/swad*.sql | tail -1
 /*
+        Version 15.52:    Nov 30, 2015	Timetable now starts at 6 a.m. instead of 7 a.m.
+					Changes in layout of timetable. (186648 lines)
         Version 15.51.4:  Nov 30, 2015	Calendar is now distributed in rows with 3 months instead of 4.
 					Changes in layout. (186644 lines)
         Version 15.51.3:  Nov 30, 2015	Responsive design in login-logout. (186641 lines)
diff --git a/swad_timetable.c b/swad_timetable.c
index 7ea3923d..98b45110 100644
--- a/swad_timetable.c
+++ b/swad_timetable.c
@@ -49,9 +49,9 @@ extern struct Globals Gbl;
 /*************************** Internal constants ******************************/
 /*****************************************************************************/
 
-#define TT_START_HOUR				  7	// Day starts at 7:00
-#define TT_HOURS_PER_DAY			 15	// From 7:00 to 22:00
-#define TT_DAYS					  7	// From monday to friday
+#define TT_START_HOUR				  6	// Day starts at 6:00
+#define TT_HOURS_PER_DAY			 16	// From 6:00 to 22:00
+#define TT_DAYS					  7	// Seven days per week
 #define TT_MAX_COLUMNS_PER_CELL			  3	// Maximum number of items (i.e. classes) in a timetable cell (1, 2, 3 or 4)
 #define TT_NUM_MINICOLUMNS_PER_DAY		  6	// Least common multiple of 1,2,3,...,TT_MAX_COLUMNS_PER_CELL
 #define TT_PERCENT_WIDTH_OF_A_MINICOLUMN	  2	// Width (%) of each minicolumn
@@ -266,7 +266,7 @@ void TT_ShowClassTimeTable (void)
      }
 
    /***** Start frame *****/
-   Lay_StartRoundFrameTable (NULL,0,Txt_TIMETABLE_TYPES[TimeTableType]);
+   Lay_StartRoundFrameTable ("100%",0,Txt_TIMETABLE_TYPES[TimeTableType]);
 
    /***** Start time table drawing *****/
    if (TimeTableType == TT_COURSE_TIMETABLE)
@@ -749,23 +749,23 @@ static void TT_DrawTimeTable (void)
      }
 
    /***** Table start *****/
-   fprintf (Gbl.F.Out,"<table style=\"min-width:700px; margin:0 auto;\">");
+   fprintf (Gbl.F.Out,"<table id=\"timetable\">");
 
    /***** Top row used for column adjustement *****/
    TT_TimeTableDrawAdjustRow ();
 
    /***** Row with day names *****/
    fprintf (Gbl.F.Out,"<tr>"
-	              "<td rowspan=\"2\" class=\"HOR RIGHT_MIDDLE\""
-	              " style=\"width:%u%%;\">"
+	              "<td rowspan=\"2\" class=\"TT_TXT RIGHT_MIDDLE\""
+	              " style=\"width:%u%%; height:40px;\">"
 	              "%u:00"
 	              "</td>",
             TT_PERCENT_WIDTH_OF_AN_HOUR_COLUMN,TT_START_HOUR);
    TT_DrawCellAlignTimeTable ();
    TT_TimeTableDrawDaysCells ();
    TT_DrawCellAlignTimeTable ();
-   fprintf (Gbl.F.Out,"<td rowspan=\"2\" class=\"HOR LEFT_MIDDLE\""
-	              " style=\"width:%u%%;\">"
+   fprintf (Gbl.F.Out,"<td rowspan=\"2\" class=\"TT_TXT LEFT_MIDDLE\""
+	              " style=\"width:%u%%; height:40px;\">"
 	              "%u:00"
 	              "</td>"
 	              "</tr>",
@@ -785,8 +785,8 @@ static void TT_DrawTimeTable (void)
 
       /* Hour */
       if (Hour % 2)
-         fprintf (Gbl.F.Out,"<td rowspan=\"2\" class=\"HOR RIGHT_MIDDLE\""
-                            " style=\"width:%u%%;\">"
+         fprintf (Gbl.F.Out,"<td rowspan=\"2\" class=\"TT_TXT RIGHT_MIDDLE\""
+                            " style=\"width:%u%%; height:40px;\">"
                             "%2u:00"
                             "</td>",
                   TT_PERCENT_WIDTH_OF_AN_HOUR_COLUMN,TT_START_HOUR + (Hour+1)/2);
@@ -843,8 +843,8 @@ static void TT_DrawTimeTable (void)
 
       /* Hour */
       if (Hour % 2)
-         fprintf (Gbl.F.Out,"<td rowspan=\"2\" class=\"HOR LEFT_MIDDLE\""
-                            " style=\"width:%u%%;\">"
+         fprintf (Gbl.F.Out,"<td rowspan=\"2\" class=\"TT_TXT LEFT_MIDDLE\""
+                            " style=\"width:%u%%; height:40px;\">"
                             "%2u:00"
                             "</td>",
                   TT_PERCENT_WIDTH_OF_AN_HOUR_COLUMN,TT_START_HOUR + (Hour+1)/2);
@@ -880,8 +880,7 @@ static void TT_TimeTableDrawAdjustRow (void)
    unsigned Minicolumn;
 
    fprintf (Gbl.F.Out,"<tr>"
-                      "<td class=\"HOR LEFT_MIDDLE\" style=\"width:%u%%;\">"
-                      "&nbsp;"
+                      "<td class=\"TT_TXT LEFT_MIDDLE\" style=\"width:%u%%;\">"
                       "</td>",
             TT_PERCENT_WIDTH_OF_AN_HOUR_COLUMN);
    TT_DrawCellAlignTimeTable ();
@@ -891,15 +890,13 @@ static void TT_TimeTableDrawAdjustRow (void)
       for (Minicolumn = 0;
 	   Minicolumn < TT_NUM_MINICOLUMNS_PER_DAY;
 	   Minicolumn++)
-         fprintf (Gbl.F.Out,"<td class=\"HOR LEFT_MIDDLE\""
+         fprintf (Gbl.F.Out,"<td class=\"TT_TXT LEFT_MIDDLE\""
                             " style=\"width:%u%%;\">"
-                            "&nbsp;"
                             "</td>",
                   TT_PERCENT_WIDTH_OF_A_MINICOLUMN);
    TT_DrawCellAlignTimeTable ();
-   fprintf (Gbl.F.Out,"<td class=\"HOR LEFT_MIDDLE\""
+   fprintf (Gbl.F.Out,"<td class=\"TT_TXT LEFT_MIDDLE\""
 	              " style=\"width:%u%%;\">"
-	              "&nbsp;"
 	              "</td>"
 	              "</tr>",
             TT_PERCENT_WIDTH_OF_AN_HOUR_COLUMN);
@@ -917,7 +914,7 @@ static void TT_TimeTableDrawDaysCells (void)
    for (Day = 0;
 	Day < TT_DAYS;
 	Day++)
-      fprintf (Gbl.F.Out,"<td colspan=\"%u\" class=\"HOR CENTER_MIDDLE\""
+      fprintf (Gbl.F.Out,"<td colspan=\"%u\" class=\"TT_TXT CENTER_MIDDLE\""
 	                 " style=\"width:%u%%;\">"
 	                 "%s"
 	                 "</td>",
@@ -986,8 +983,7 @@ static unsigned TT_TimeTableCalculateColsToDraw (unsigned Day,unsigned Hour)
 
 static void TT_DrawCellAlignTimeTable (void)
   {
-   fprintf (Gbl.F.Out,"<td class=\"HOR LEFT_MIDDLE\" style=\"width:%u%%;\">"
-	              "&nbsp;"
+   fprintf (Gbl.F.Out,"<td class=\"TT_TXT LEFT_MIDDLE\" style=\"width:%u%%;\">"
 	              "</td>",
             TT_PERCENT_WIDTH_OF_A_SEPARATION_COLUMN);
   }
@@ -1032,13 +1028,13 @@ static void TT_TimeTableDrawCell (unsigned Day,unsigned Hour,unsigned Column,uns
    /***** Compute row span and background color depending on hour type *****/
    switch (HourType)
      {
-      case TT_FREE_HOUR:		// Se escribe una casilla libre
-         RowSpan = 1;
+      case TT_FREE_HOUR:	// Free cell written
+	 RowSpan = 1;
 	 break;
-      case TT_FIRST_HOUR:	// Se escribe una casilla normal
+      case TT_FIRST_HOUR:	// Normal cell written
 	 RowSpan = Duration;
 	 break;
-      case TT_NEXT_HOUR:	// No se escribe nada
+      case TT_NEXT_HOUR:	// Nothing written
 	 break;
      }
 
@@ -1093,14 +1089,9 @@ static void TT_TimeTableDrawCell (unsigned Day,unsigned Hour,unsigned Column,uns
      {
       case TT_CRS_SHOW:
       case TT_TUT_SHOW:
-	 if (HourType == TT_FREE_HOUR) // If cell is empty...
-	    fprintf (Gbl.F.Out,"<img src=\"%s/tr1x16.gif\""
-	                       " alt=\"\" title=\"\""
-		               " style=\"width:1px; height:20px;\" />",
-                     Gbl.Prefs.IconsURL);
-	 else
+	 if (HourType != TT_FREE_HOUR) // If cell is not empty...
 	   {
-	    fprintf (Gbl.F.Out,"<span class=\"HOR\">");
+	    fprintf (Gbl.F.Out,"<span class=\"TT_TXT\">");
 	    if (Gbl.CurrentAct == ActSeeMyTimTbl ||
                 Gbl.CurrentAct == ActPrnMyTimTbl)
               {