diff --git a/view/theme/frio/config.php b/view/theme/frio/config.php
index 6e5aca1bad..8add86ea05 100644
--- a/view/theme/frio/config.php
+++ b/view/theme/frio/config.php
@@ -1,81 +1,121 @@
 <?php
 
 use Friendica\App;
+use Friendica\Core\Config;
+use Friendica\Core\PConfig;
 use Friendica\Core\System;
 
 require_once('view/theme/frio/php/Image.php');
 
-function theme_content(App $a) {
-	if (!local_user()) {
-		return;
-	}
-	$arr = array();
-
-	$arr["schema"]		= get_pconfig(local_user(),'frio', 'schema');
-	$arr["nav_bg"]		= get_pconfig(local_user(),'frio', 'nav_bg' );
-	$arr["nav_icon_color"]	= get_pconfig(local_user(),'frio', 'nav_icon_color' );
-	$arr["link_color"]	= get_pconfig(local_user(),'frio', 'link_color' );
-	$arr["bgcolor"]		= get_pconfig(local_user(),'frio', 'background_color' );
-	$arr["contentbg_transp"] = get_pconfig(local_user(),'frio', 'contentbg_transp' );
-	$arr["background_image"] = get_pconfig(local_user(),'frio', 'background_image' );
-	$arr["bg_image_option"] = get_pconfig(local_user(),'frio', 'bg_image_option' );
-
-	return frio_form($arr);
-}
-
 function theme_post(App $a) {
 	if (!local_user()) {
 		return;
 	}
 
 	if (isset($_POST['frio-settings-submit'])) {
-		set_pconfig(local_user(), 'frio', 'schema',		$_POST["frio_schema"]);
-		set_pconfig(local_user(), 'frio', 'nav_bg',		$_POST["frio_nav_bg"]);
-		set_pconfig(local_user(), 'frio', 'nav_icon_color',	$_POST["frio_nav_icon_color"]);
-		set_pconfig(local_user(), 'frio', 'link_color',		$_POST["frio_link_color"]);
-		set_pconfig(local_user(), 'frio', 'background_color',	$_POST["frio_background_color"]);
-		set_pconfig(local_user(), 'frio', 'contentbg_transp',	$_POST["frio_contentbg_transp"]);
-		set_pconfig(local_user(), 'frio', 'background_image',	$_POST["frio_background_image"]);
-		set_pconfig(local_user(), 'frio', 'bg_image_option',	$_POST["frio_bg_image_option"]);
+		PConfig::set(local_user(), 'frio', 'schema',           $_POST["frio_schema"]);
+		PConfig::set(local_user(), 'frio', 'nav_bg',           $_POST["frio_nav_bg"]);
+		PConfig::set(local_user(), 'frio', 'nav_icon_color',   $_POST["frio_nav_icon_color"]);
+		PConfig::set(local_user(), 'frio', 'link_color',       $_POST["frio_link_color"]);
+		PConfig::set(local_user(), 'frio', 'background_color', $_POST["frio_background_color"]);
+		PConfig::set(local_user(), 'frio', 'contentbg_transp', $_POST["frio_contentbg_transp"]);
+		PConfig::set(local_user(), 'frio', 'background_image', $_POST["frio_background_image"]);
+		PConfig::set(local_user(), 'frio', 'bg_image_option',  $_POST["frio_bg_image_option"]);
+		PConfig::set(local_user(), 'frio', 'css_modified',     time());
 	}
 }
 
+function theme_admin_post(App $a) {
+	if (!local_user()) {
+		return;
+	}
+
+	if (isset($_POST['frio-settings-submit'])) {
+		Config::set('frio', 'schema',           $_POST["frio_schema"]);
+		Config::set('frio', 'nav_bg',           $_POST["frio_nav_bg"]);
+		Config::set('frio', 'nav_icon_color',   $_POST["frio_nav_icon_color"]);
+		Config::set('frio', 'link_color',       $_POST["frio_link_color"]);
+		Config::set('frio', 'background_color', $_POST["frio_background_color"]);
+		Config::set('frio', 'contentbg_transp', $_POST["frio_contentbg_transp"]);
+		Config::set('frio', 'background_image', $_POST["frio_background_image"]);
+		Config::set('frio', 'bg_image_option',  $_POST["frio_bg_image_option"]);
+		Config::set('frio', 'css_modified',     time());
+	}
+}
+
+function theme_content(App $a) {
+	if (!local_user()) {
+		return;
+	}
+	$arr = array();
+
+	$arr["schema"]           = PConfig::get(local_user(), 'frio', 'schema');
+	$arr["nav_bg"]           = PConfig::get(local_user(), 'frio', 'nav_bg');
+	$arr["nav_icon_color"]   = PConfig::get(local_user(), 'frio', 'nav_icon_color');
+	$arr["link_color"]       = PConfig::get(local_user(), 'frio', 'link_color');
+	$arr["bgcolor"]          = PConfig::get(local_user(), 'frio', 'background_color');
+	$arr["contentbg_transp"] = PConfig::get(local_user(), 'frio', 'contentbg_transp');
+	$arr["background_image"] = PConfig::get(local_user(), 'frio', 'background_image');
+	$arr["bg_image_option"]  = PConfig::get(local_user(), 'frio', 'bg_image_option');
+
+	return frio_form($arr);
+}
+
+function theme_admin(App $a) {
+	if (!local_user()) {
+		return;
+	}
+	$arr = array();
+
+	$arr["schema"]           = Config::get('frio', 'schema');
+	$arr["nav_bg"]           = Config::get('frio', 'nav_bg');
+	$arr["nav_icon_color"]   = Config::get('frio', 'nav_icon_color');
+	$arr["link_color"]       = Config::get('frio', 'link_color');
+	$arr["bgcolor"]          = Config::get('frio', 'background_color');
+	$arr["contentbg_transp"] = Config::get('frio', 'contentbg_transp');
+	$arr["background_image"] = Config::get('frio', 'background_image');
+	$arr["bg_image_option"]  = Config::get('frio', 'bg_image_option');
+
+	return frio_form($arr);
+}
+
 function frio_form($arr) {
 	require_once("view/theme/frio/php/schema.php");
 
 	$scheme_info = get_schema_info($arr["schema"]);
 	$disable = $scheme_info["overwrites"];
-	if (!is_array($disable)) $disable = array();
+	if (!is_array($disable)) {
+		$disable = array();
+	}
 
 	$scheme_choices = array();
 	$scheme_choices["---"] = t("Default");
 	$files = glob('view/theme/frio/schema/*.php');
-	if($files) {
-		foreach($files as $file) {
+	if ($files) {
+		foreach ($files as $file) {
 			$f = basename($file, ".php");
-			if($f != 'default') {
+			if ($f != 'default') {
 				$scheme_name = $f;
 				$scheme_choices[$f] = $scheme_name;
 			}
 		}
 	}
 
-	$background_image_help = "<strong>" . t("Note: "). "</strong>".t("Check image permissions if all users are allowed to visit the image");
-
+	$background_image_help = "<strong>" . t("Note"). ": </strong>".t("Check image permissions if all users are allowed to visit the image");
 
 	$t = get_markup_template('theme_settings.tpl');
 	$o .= replace_macros($t, array(
-		'$submit'		=> t('Submit'),
-		'$baseurl'		=> System::baseUrl(),
-		'$title'		=> t("Theme settings"),
-		'$schema'		=> array('frio_schema',		t("Select scheme"),			$arr["schema"], '', $scheme_choices),
-		'$nav_bg'		=> array_key_exists("nav_bg", $disable) ? "" : array('frio_nav_bg',		t('Navigation bar background color'),	$arr['nav_bg']),
-		'$nav_icon_color'	=> array_key_exists("nav_icon_color", $disable) ? "" : array('frio_nav_icon_color', t('Navigation bar icon color '),	$arr['nav_icon_color']),
-		'$link_color'		=> array_key_exists("link_color", $disable) ? "" : array('frio_link_color',	t('Link color'),			$arr['link_color'],		'', $link_colors),
-		'$bgcolor'		=> array_key_exists("bgcolor", $disable) ? "" : array('frio_background_color', t('Set the background color'),	$arr['bgcolor']),
-		'$contentbg_transp'	=> array_key_exists("contentbg_transp", $disable) ? "" : array('frio_contentbg_transp', t("Content background transparency"), ($arr["contentbg_transp"] ? $arr["contentbg_transp"] : 0 )),
-		'$background_image'	=> array_key_exists("background_image", $disable ) ? "" : array('frio_background_image', t('Set the background image'),	$arr['background_image'], $background_image_help),
-		'$bg_image_options'	=> Image::get_options($arr),
+		'$submit'           => t('Submit'),
+		'$baseurl'          => System::baseUrl(),
+		'$title'            => t("Theme settings"),
+		'$schema'           => array('frio_schema', t("Select scheme"), $arr["schema"], '', $scheme_choices),
+		'$nav_bg'           => array_key_exists("nav_bg", $disable) ? "" : array('frio_nav_bg', t('Navigation bar background color'), $arr['nav_bg']),
+		'$nav_icon_color'   => array_key_exists("nav_icon_color", $disable) ? "" : array('frio_nav_icon_color', t('Navigation bar icon color '), $arr['nav_icon_color']),
+		'$link_color'       => array_key_exists("link_color", $disable) ? "" : array('frio_link_color', t('Link color'), $arr['link_color'], '', $link_colors),
+		'$bgcolor'          => array_key_exists("bgcolor", $disable) ? "" : array('frio_background_color', t('Set the background color'), $arr['bgcolor']),
+		'$contentbg_transp' => array_key_exists("contentbg_transp", $disable) ? "" : array('frio_contentbg_transp', t("Content background transparency"), ((isset($arr["contentbg_transp"]) && $arr["contentbg_transp"] != "") ? $arr["contentbg_transp"] : 100)),
+		'$background_image' => array_key_exists("background_image", $disable ) ? "" : array('frio_background_image', t('Set the background image'), $arr['background_image'], $background_image_help),
+		'$bg_image_options' => Image::get_options($arr),
 	));
 
 	return $o;
diff --git a/view/theme/frio/css/style.css b/view/theme/frio/css/style.css
index f15faf3896..ab8e3d5a53 100644
--- a/view/theme/frio/css/style.css
+++ b/view/theme/frio/css/style.css
@@ -2817,6 +2817,14 @@ section.help-content-wrapper li {
     font-size: 0.96em;
 }
 
+/*Admin Page*/
+#adminpage #frio_background_image .image-select {
+    display: none;
+}
+#adminpage #frio_background_image.input-group {
+    display: block;
+}
+
 /* Register Page*/
 #register-openid-wrapper, #register-name-wrapper, #register-invite-wrapper, #profile-publish-wrapper {
     margin-top: 20px;
diff --git a/view/theme/frio/style.php b/view/theme/frio/style.php
index cc77f8234a..04379b244e 100644
--- a/view/theme/frio/style.php
+++ b/view/theme/frio/style.php
@@ -1,40 +1,77 @@
 <?php
-require_once('view/theme/frio/php/PHPColors/Color.php');
+require_once 'view/theme/frio/php/PHPColors/Color.php';
 
+use Friendica\Core\Config;
+use Friendica\Core\PConfig;
 
-if(! $a->install) {
-	// Get the UID of the channel owner
+$schemecss = "";
+$schemecssfile = false;
+$scheme_modified = 0;
+
+if (! $a->install) {
+	// Get the UID of the profile owner.
 	$uid = get_theme_uid();
-	if($uid) {
-		load_pconfig($uid,'frio');
+	if ($uid) {
+		PConfig::load($uid, 'frio');
+
+		// Load the profile owners pconfig.
+		$schema           = PConfig::get($uid, "frio", "schema");
+		$nav_bg           = PConfig::get($uid, "frio", "nav_bg");
+		$nav_icon_color   = PConfig::get($uid, "frio", "nav_icon_color");
+		$link_color       = PConfig::get($uid, "frio", "link_color");
+		$bgcolor          = PConfig::get($uid, "frio", "background_color");
+		$contentbg_transp = PConfig::get($uid, "frio", "contentbg_transp");
+		$background_image = PConfig::get($uid, "frio", "background_image");
+		$bg_image_option  = PConfig::get($uid, "frio", "bg_image_option");
+		$modified         = PConfig::get($uid, "frio", "css_modified");
+
+		// There is maybe the case that the user did never modify the theme settings.
+		// In this case we store the present time.
+		if (empty($modified)) {
+			PConfig::set($uid, 'frio', 'css_modified', time());
+		}
+	} else {
+		Config::load('frio');
+
+		// Load frios system config.
+		$schema           = Config::get("frio", "schema");
+		$nav_bg           = Config::get("frio", "nav_bg");
+		$nav_icon_color   = Config::get("frio", "nav_icon_color");
+		$link_color       = Config::get("frio", "link_color");
+		$bgcolor          = Config::get("frio", "background_color");
+		$contentbg_transp = Config::get("frio", "contentbg_transp");
+		$background_image = Config::get("frio", "background_image");
+		$bg_image_option  = Config::get("frio", "bg_image_option");
+		$modified         = Config::get("frio", "css_modified");
+
+		// There is maybe the case that the user did never modify the theme settings.
+		// In this case we store the present time.
+		if (empty($modified)) {
+			Config::set('frio', 'css_modified', time());
+		}
 	}
-	// Load the owners pconfig
-	$schema		= get_pconfig($uid, "frio", "schema");
-	$nav_bg		= get_pconfig($uid, "frio", "nav_bg");
-	$nav_icon_color = get_pconfig($uid, "frio", "nav_icon_color");
-	$link_color	= get_pconfig($uid, "frio", "link_color");
-	$bgcolor	= get_pconfig($uid, "frio", "background_color");
-	$contentbg_transp = get_pconfig($uid, "frio", "contentbg_transp");
-	$background_image = get_pconfig($uid, "frio", "background_image");
-	$bg_image_option = get_pconfig($uid, "frio", "bg_image_option");
 }
 
 // Now load the scheme.  If a value is changed above, we'll keep the settings
 // If not, we'll keep those defined by the schema
 // Setting $schema to '' wasn't working for some reason, so we'll check it's
 // not --- like the mobile theme does instead.
-// Allow layouts to over-ride the schema
-if($_REQUEST['schema']) {
+// Allow layouts to over-ride the schema.
+if ($_REQUEST['schema']) {
 	$schema = $_REQUEST['schema'];
 }
+
+// Sanitize the data.
+$schema = !empty($schema) ? basename($schema) : "";
+
+
 if (($schema) && ($schema != '---')) {
-	// Check it exists, because this setting gets distributed to clones
-	if(file_exists('view/theme/frio/schema/' . $schema . '.php')) {
+	if (file_exists('view/theme/frio/schema/' . $schema . '.php')) {
 		$schemefile = 'view/theme/frio/schema/' . $schema . '.php';
-		require_once ($schemefile);
+		require_once $schemefile;
 	}
-	if(file_exists('view/theme/frio/schema/' . $schema . '.css')) {
-		$schemecss = file_get_contents('view/theme/frio/schema/' . $schema . '.css');
+	if (file_exists('view/theme/frio/schema/' . $schema . '.css')) {
+		$schemecssfile = 'view/theme/frio/schema/' . $schema . '.css';
 	}
 }
 
@@ -44,57 +81,54 @@ if (($schema) && ($schema != '---')) {
 if (! $schema) {
 	if(file_exists('view/theme/frio/schema/default.php')) {
 		$schemefile = 'view/theme/frio/schema/default.php';
-		require_once ($schemefile);
+		require_once $schemefile;
 	}
 	if(file_exists('view/theme/frio/schema/default.css')) {
-		$schemecss = file_get_contents('view/theme/frio/schema/default.css');
+		$schemecssfile = 'view/theme/frio/schema/default.css';
 	}
 }
 
 //Set some defaults - we have to do this after pulling owner settings, and we have to check for each setting
 //individually.  If we don't, we'll have problems if a user has set one, but not all options.
-if(! $nav_bg)
-	$nav_bg = "#708fa0";
-if(! $nav_icon_color)
-	$nav_icon_color = "#fff";
-if(! $link_color)
-	$link_color = "#6fdbe8";
-if(! $bgcolor)
-	$bgcolor = "#ededed";
-if(! $contentbg_transp)
-	$contentbg_transp = 100;
-if(! $background_image)
-	$background_image ='';
+$nav_bg           = (empty($nav_bg)           ? "#708fa0"      : $nav_bg);
+$nav_icon_color   = (empty($nav_icon_color)   ? "#fff"         : $nav_icon_color);
+$link_color       = (empty($link_color)       ? "#6fdbe8"      : $link_color);
+$bgcolor          = (empty($bgcolor)          ? "#ededed"      : $bgcolor);
+// The background image can not be empty. So we use a dummy jpg if no image was set.
+$background_image = (empty($background_image) ? 'img/none.jpg' : $background_image);
+$modified         = (empty($modified)         ? time()         :$modified);
 
-// Calculate some colors in dependance of existing colors
+$contentbg_transp = ((isset($contentbg_transp) && $contentbg_transp != "") ? $contentbg_transp : 100);
+
+// Calculate some colors in dependance of existing colors.
 // Some colors are calculated to don't have too many selection
-// fields in the theme settings
-if(! $menu_background_hover_color) {
+// fields in the theme settings.
+if (! $menu_background_hover_color) {
 	$mbhc = new Color($nav_bg);
 	$mcolor = $mbhc->getHex();
 
-	if($mbhc->isLight($mcolor, 75)) {
+	if ($mbhc->isLight($mcolor, 75)) {
 		$menu_is = 'light';
 		$menu_background_hover_color = '#' . $mbhc->darken(5);
 	} else {
 		$menu_is = 'dark';
 		$menu_background_hover_color = '#' . $mbhc->lighten(5);
-	//$menu_background_hover_color = "#628394";
 	}
 }
-if(! $nav_icon_hover_color) {
+if (! $nav_icon_hover_color) {
 	$nihc = new Color($nav_bg);
 
-	if($nihc->isLight())
+	if ($nihc->isLight()) {
 		$nav_icon_hover_color = '#' . $nihc->darken(10);
-	else
+	} else {
 		$nav_icon_hover_color = '#' . $nihc->lighten(10);
+	}
 }
-if(! $link_hover_color) {
+if (! $link_hover_color) {
 	$lhc = new Color($link_color);
 	$lcolor = $lhc->getHex();
 
-	if($lhc->isLight($lcolor, 75)) {
+	if ($lhc->isLight($lcolor, 75)) {
 		$link_hover_color = '#' . $lhc->darken(5);
 	} else {
 		$link_hover_color = '#' . $lhc->lighten(5);
@@ -102,7 +136,7 @@ if(! $link_hover_color) {
 
 }
 
-// Convert $bg_image_options into css
+// Convert $bg_image_options into css.
 switch ($bg_image_option) {
 	case "stretch":
 		$background_size_img = "100%";
@@ -122,32 +156,59 @@ switch ($bg_image_option) {
 		break;
 }
 
-// Convert transparency level from percentage to opacity value
+// Convert transparency level from percentage to opacity value.
 $contentbg_transp = $contentbg_transp / 100;
 
+$options = array (
+	'$nav_bg'                      => $nav_bg,
+	'$nav_icon_color'              => $nav_icon_color,
+	'$nav_icon_hover_color'        => $nav_icon_hover_color,
+	'$link_color'                  => $link_color,
+	'$link_hover_color'            => $link_hover_color,
+	'$menu_background_hover_color' => $menu_background_hover_color,
+	'$btn_primary_color'           => $nav_icon_color,
+	'$btn_primary_hover_color'     => $menu_background_hover_color,
+	'$bgcolor'                     => $bgcolor,
+	'$contentbg_transp'            => $contentbg_transp,
+	'$background_image'            => $background_image,
+	'$background_size_img'         => $background_size_img,
+);
 
-// Apply the settings
-if(file_exists('view/theme/frio/css/style.css')) {
-	$x = file_get_contents('view/theme/frio/css/style.css');
+$css_tpl = file_get_contents('view/theme/frio/css/style.css');
 
-	$options = array (
-		'$nav_bg'			=> $nav_bg,
-		'$nav_icon_color'		=> $nav_icon_color,
-		'$nav_icon_hover_color'		=> $nav_icon_hover_color,
-		'$link_color'			=> $link_color,
-		'$link_hover_color'		=> $link_hover_color,
-		'$menu_background_hover_color'	=> $menu_background_hover_color,
-		'$btn_primary_color'		=> $nav_icon_color,
-		'$btn_primary_hover_color'	=> $menu_background_hover_color,
-		'$bgcolor'			=> $bgcolor,
-		'$contentbg_transp'		=> $contentbg_transp,
-		'$background_image'		=> $background_image,
-		'$background_size_img'		=> $background_size_img,
-	);
-
-	echo str_replace(array_keys($options), array_values($options), $x);
+// Get the content of the scheme css file and the time of the last file change.
+if ($schemecssfile) {
+	$css_tpl .= file_get_contents($schemecssfile);
+	$scheme_modified = filemtime($schemecssfile);
 }
 
-if($schemecss) {
-	echo $schemecss;
+// We need to check which is the most recent css data.
+// We will use this time later to decide if we load the cached or fresh css data.
+if ($scheme_modified > $modified) {
+	$modified = $scheme_modified;
 }
+// Apply the settings to the css template.
+$css = str_replace(array_keys($options), array_values($options), $css_tpl);
+
+$modified = gmdate('r', $modified);
+
+$etag = md5($css);
+
+// Set a header for caching.
+header('Cache-Control: public');
+header('ETag: "'.$etag.'"');
+header('Last-Modified: '.$modified);
+
+// Only send the CSS file if it was changed.
+if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) || isset($_SERVER['HTTP_IF_NONE_MATCH'])) {
+	$cached_modified = gmdate('r', strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']));
+	$cached_etag = str_replace(array('"', "-gzip"), array('', ''),
+				stripslashes($_SERVER['HTTP_IF_NONE_MATCH']));
+
+	if (($cached_modified == $modified) && ($cached_etag == $etag)) {
+		header('HTTP/1.1 304 Not Modified');
+		exit();
+	}
+}
+
+echo $css;
diff --git a/view/theme/frio/templates/theme_settings.tpl b/view/theme/frio/templates/theme_settings.tpl
index d4438caa8c..92b463694f 100644
--- a/view/theme/frio/templates/theme_settings.tpl
+++ b/view/theme/frio/templates/theme_settings.tpl
@@ -31,7 +31,7 @@
 </div>
 
 <script type="text/javascript">
-	$(function(){
+	$(document).ready(function() {
 		$("#frio_nav_bg, #frio_nav_icon_color, #frio_background_color, #frio_link_color").colorpicker({format: 'hex', align: 'left'});
 
 		// show image options when user user starts to type the address of the image
@@ -60,6 +60,13 @@
 			theme: 'theme-frio',
 		});
 
+		// The position of the slider is wrong calculated on hidden elements.
+		// So set an event listener toggle and update the jRange value.
+		$(document).on('click', '#custom-settings-title a', function() {
+			var bgTransp = $('#frio_contentbg_transp').val();
+			$('.slider-input').jRange('setValue', bgTransp);
+		});
+
 	});
 </script>
 
diff --git a/view/theme/frio/theme.php b/view/theme/frio/theme.php
index a9423e09d5..753a8bc482 100644
--- a/view/theme/frio/theme.php
+++ b/view/theme/frio/theme.php
@@ -37,7 +37,7 @@ function frio_init(App $a) {
 				var is_mobile = 1;
 			</script>
 EOT;
-			}
+}
 
 	if ($style == "")
 		$style = get_config('frio', 'style');