diff --git a/lib/weblib.php b/lib/weblib.php
index a9a53d1c3e1..5985c26c2df 100644
--- a/lib/weblib.php
+++ b/lib/weblib.php
@@ -780,6 +780,24 @@ function print_footer ($course=NULL) {
     include ("$CFG->dirroot/theme/$CFG->theme/footer.html");
 }
 
+function style_sheet_setup($lastmodified, $lifetime, $themename="") {
+
+    global $CFG;
+
+    header("Last-Modified: " . gmdate("D, d M Y H:i:s", $lastmodified) . " GMT");
+    header("Expires: " . gmdate("D, d M Y H:i:s", time() + $lifetime) . " GMT");
+    header("Cache-control: max_age = $lifetime"); 
+    header("Pragma: ");
+    header("Content-type: text/css");  // Correct MIME type
+
+    if (!empty($themename)) {
+        $CFG->theme = $themename;
+    }
+
+    return "$CFG->wwwroot/theme/$CFG->theme";
+
+}
+
 
 function user_login_string($course, $user=NULL) {
     global $USER, $CFG;
diff --git a/theme/brightretro/styles.php b/theme/brightretro/styles.php
index 9f41f51e74d..d7e8d26ebe0 100644
--- a/theme/brightretro/styles.php
+++ b/theme/brightretro/styles.php
@@ -2,15 +2,9 @@
 
 /// We use PHP so we can do value substitutions into the styles
 
+    $nomoodlecookie = true;
     require_once("../../config.php"); 
-
-    header("Content-type: text/css");  /// Correct MIME type
-
-    if (isset($themename)) {
-        $CFG->theme = $themename;
-    }
-
-    $themeurl = "$CFG->wwwroot/theme/$CFG->theme";
+    $themeurl = style_sheet_setup(filemtime("styles.php"), 300, $themename);
 
 
 /// From here on it's nearly a normal stylesheet. 
diff --git a/theme/cordoroyblue/styles.php b/theme/cordoroyblue/styles.php
index 59bb199596f..5bd43b93141 100644
--- a/theme/cordoroyblue/styles.php
+++ b/theme/cordoroyblue/styles.php
@@ -2,15 +2,10 @@
 
 /// We use PHP so we can do value substitutions into the styles
 
-    require_once("../../config.php"); 
+    $nomoodlecookie = true;
+    require_once("../../config.php");
+    $themeurl = style_sheet_setup(filemtime("styles.php"), 300, $themename);
 
-    header("Content-type: text/css");  /// Correct MIME type
-
-    if (isset($themename)) {
-        $CFG->theme = $themename;
-    }
-
-    $themeurl = "$CFG->wwwroot/theme/$CFG->theme";
 
 /// From here on it's nearly a normal stylesheet. 
 /// First are some CSS definitions for normal tags, 
diff --git a/theme/garden/styles.php b/theme/garden/styles.php
index 169bdc6e22c..5719fef320a 100755
--- a/theme/garden/styles.php
+++ b/theme/garden/styles.php
@@ -2,15 +2,9 @@
 
 /// We use PHP so we can do value substitutions into the styles
 
-    require_once("../../config.php"); 
-
-    header("Content-type: text/css");  // Correct MIME type
-
-    if (isset($themename)) {
-        $CFG->theme = $themename;
-    }
-
-    $themeurl = "$CFG->wwwroot/theme/$CFG->theme";
+    $nomoodlecookie = true;
+    require_once("../../config.php");
+    $themeurl = style_sheet_setup(filemtime("styles.php"), 300, $themename);
 
 /// From here on it's nearly a normal stylesheet. 
 /// First are some CSS definitions for normal tags, 
diff --git a/theme/oceanblue/styles.php b/theme/oceanblue/styles.php
index 07e4e559dce..dd861fde7b1 100644
--- a/theme/oceanblue/styles.php
+++ b/theme/oceanblue/styles.php
@@ -2,15 +2,9 @@
 
 /// We use PHP so we can do value substitutions into the styles
 
-    require_once("../../config.php"); 
-
-    header("Content-type: text/css");  // Correct MIME type
-
-    if (isset($themename)) {
-        $CFG->theme = $themename;
-    }
-
-    $themeurl = "$CFG->wwwroot/theme/$CFG->theme";
+    $nomoodlecookie = true;
+    require_once("../../config.php");
+    $themeurl = style_sheet_setup(filemtime("styles.php"), 300, $themename);
 
 /// From here on it's nearly a normal stylesheet. 
 /// First are some CSS definitions for normal tags, 
diff --git a/theme/poweraid/styles.php b/theme/poweraid/styles.php
index 0a1e9794e07..8970299c09f 100644
--- a/theme/poweraid/styles.php
+++ b/theme/poweraid/styles.php
@@ -26,13 +26,9 @@
 
 /* We use PHP so we can do value substitutions into the styles */
 
-	require_once("../../config.php"); 
-
-	if (isset($themename)) {
-		$CFG->theme = $themename;
-	}
-
-	$themeurl = "$CFG->wwwroot/theme/$CFG->theme";
+    $nomoodlecookie = true;
+    require_once("../../config.php");
+    $themeurl = style_sheet_setup(filemtime("styles.php"), 300, $themename);
 
 /*
    From here on it's nearly a normal stylesheet.
diff --git a/theme/standard/styles.php b/theme/standard/styles.php
index b89b8aba50b..731de212206 100644
--- a/theme/standard/styles.php
+++ b/theme/standard/styles.php
@@ -2,15 +2,9 @@
 
 /// We use PHP so we can do value substitutions into the styles
 
+    $nomoodlecookie = true;
     require_once("../../config.php"); 
-
-    header("Content-type: text/css");  // Correct MIME type
-
-    if (isset($themename)) {
-        $CFG->theme = $themename;
-    }
-
-    $themeurl = "$CFG->wwwroot/theme/$CFG->theme";
+    $themeurl = style_sheet_setup(filemtime("styles.php"), 300, $themename);
 
 /// From here on it's nearly a normal stylesheet. 
 /// First are some CSS definitions for normal tags, 
diff --git a/theme/standardblue/styles.php b/theme/standardblue/styles.php
index b89b8aba50b..3025f069e51 100644
--- a/theme/standardblue/styles.php
+++ b/theme/standardblue/styles.php
@@ -2,15 +2,9 @@
 
 /// We use PHP so we can do value substitutions into the styles
 
-    require_once("../../config.php"); 
-
-    header("Content-type: text/css");  // Correct MIME type
-
-    if (isset($themename)) {
-        $CFG->theme = $themename;
-    }
-
-    $themeurl = "$CFG->wwwroot/theme/$CFG->theme";
+    $nomoodlecookie = true;
+    require_once("../../config.php");
+    $themeurl = style_sheet_setup(filemtime("styles.php"), 300, $themename);
 
 /// From here on it's nearly a normal stylesheet. 
 /// First are some CSS definitions for normal tags, 
diff --git a/theme/standardgreen/styles.php b/theme/standardgreen/styles.php
index b89b8aba50b..3025f069e51 100644
--- a/theme/standardgreen/styles.php
+++ b/theme/standardgreen/styles.php
@@ -2,15 +2,9 @@
 
 /// We use PHP so we can do value substitutions into the styles
 
-    require_once("../../config.php"); 
-
-    header("Content-type: text/css");  // Correct MIME type
-
-    if (isset($themename)) {
-        $CFG->theme = $themename;
-    }
-
-    $themeurl = "$CFG->wwwroot/theme/$CFG->theme";
+    $nomoodlecookie = true;
+    require_once("../../config.php");
+    $themeurl = style_sheet_setup(filemtime("styles.php"), 300, $themename);
 
 /// From here on it's nearly a normal stylesheet. 
 /// First are some CSS definitions for normal tags, 
diff --git a/theme/standardlogo/styles.php b/theme/standardlogo/styles.php
index b89b8aba50b..3025f069e51 100644
--- a/theme/standardlogo/styles.php
+++ b/theme/standardlogo/styles.php
@@ -2,15 +2,9 @@
 
 /// We use PHP so we can do value substitutions into the styles
 
-    require_once("../../config.php"); 
-
-    header("Content-type: text/css");  // Correct MIME type
-
-    if (isset($themename)) {
-        $CFG->theme = $themename;
-    }
-
-    $themeurl = "$CFG->wwwroot/theme/$CFG->theme";
+    $nomoodlecookie = true;
+    require_once("../../config.php");
+    $themeurl = style_sheet_setup(filemtime("styles.php"), 300, $themename);
 
 /// From here on it's nearly a normal stylesheet. 
 /// First are some CSS definitions for normal tags, 
diff --git a/theme/standardred/styles.php b/theme/standardred/styles.php
index b89b8aba50b..3025f069e51 100644
--- a/theme/standardred/styles.php
+++ b/theme/standardred/styles.php
@@ -2,15 +2,9 @@
 
 /// We use PHP so we can do value substitutions into the styles
 
-    require_once("../../config.php"); 
-
-    header("Content-type: text/css");  // Correct MIME type
-
-    if (isset($themename)) {
-        $CFG->theme = $themename;
-    }
-
-    $themeurl = "$CFG->wwwroot/theme/$CFG->theme";
+    $nomoodlecookie = true;
+    require_once("../../config.php");
+    $themeurl = style_sheet_setup(filemtime("styles.php"), 300, $themename);
 
 /// From here on it's nearly a normal stylesheet. 
 /// First are some CSS definitions for normal tags, 
diff --git a/theme/standardwhite/styles.php b/theme/standardwhite/styles.php
index b89b8aba50b..3025f069e51 100644
--- a/theme/standardwhite/styles.php
+++ b/theme/standardwhite/styles.php
@@ -2,15 +2,9 @@
 
 /// We use PHP so we can do value substitutions into the styles
 
-    require_once("../../config.php"); 
-
-    header("Content-type: text/css");  // Correct MIME type
-
-    if (isset($themename)) {
-        $CFG->theme = $themename;
-    }
-
-    $themeurl = "$CFG->wwwroot/theme/$CFG->theme";
+    $nomoodlecookie = true;
+    require_once("../../config.php");
+    $themeurl = style_sheet_setup(filemtime("styles.php"), 300, $themename);
 
 /// From here on it's nearly a normal stylesheet. 
 /// First are some CSS definitions for normal tags,