diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..9ea0f13
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+.*
+!.gitignore
diff --git a/Module.php b/Module.php
index 14cff4e..46e0f3a 100644
--- a/Module.php
+++ b/Module.php
@@ -25,7 +25,7 @@ public function getDescription()
     // Link to configuration page
     public function getConfigUrl()
     {
-        return Url::to(['/flex-theme/config']);
+        return Url::to(['/flex-theme/admin']);
     }
 
     // Module Activation
diff --git a/controllers/ConfigController.php b/controllers/AdminController.php
similarity index 91%
rename from controllers/ConfigController.php
rename to controllers/AdminController.php
index dbbf3ba..5b0d4d7 100644
--- a/controllers/ConfigController.php
+++ b/controllers/AdminController.php
@@ -8,7 +8,7 @@
 use humhub\modules\flexTheme\models\AdvancedSettings;
 use Yii;
 
-class ConfigController extends \humhub\modules\admin\components\Controller
+class AdminController extends \humhub\modules\admin\components\Controller
 {
     public $subLayout = '@flex-theme/views/layouts/admin';
 
@@ -19,7 +19,7 @@ public function actionIndex()
         if ($form->load(Yii::$app->request->post()) && $form->save()) {
             $this->view->saved();
             // Redirect instead of render to make browser reload CSS
-            return $this->redirect(['/flex-theme/config']);
+            return $this->redirect(['/flex-theme/admin']);
         }
 
         return $this->render('index', ['model' => $form]);
@@ -36,7 +36,7 @@ public function actionColors()
                 $this->view->saved();
             }
             // Redirect instead of render to make browser reload CSS
-            return $this->redirect(['/flex-theme/config/colors']);
+            return $this->redirect(['/flex-theme/admin/colors']);
         }
 
         return $this->render('colors', ['model' => $form]);
@@ -53,7 +53,7 @@ public function actionDarkColors()
                 $this->view->saved();
             }
             // Redirect instead of render to make browser reload CSS
-            return $this->redirect(['/flex-theme/config/dark-colors']);
+            return $this->redirect(['/flex-theme/admin/dark-colors']);
         }
 
         return $this->render('dark-colors', ['model' => $form]);
@@ -90,7 +90,7 @@ public function actionAdvanced()
             if ($config->save() && $colorSettings->save() && $darkColorSettings->save()) {
                 $this->view->saved();
                 // Redirect instead of render to make browser reload CSS
-                return $this->redirect(['/flex-theme/config/advanced']);
+                return $this->redirect(['/flex-theme/admin/advanced']);
             }
         }
 
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 1c12074..ca44b2b 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -1,4 +1,5 @@
 ## TBA
+- Fix #39: rounding issue in ColorHelper - thanks to @marc-farre
 - Fix #42: Division by zero (when trying to lighten white color)
 - Fix #43: Invalid faded color calculated from 3 digits base color
 - Enh #45: Add option to reset all colors of the current form
diff --git a/docs/INSTALLATION.md b/docs/INSTALLATION.md
deleted file mode 100644
index 745f0bd..0000000
--- a/docs/INSTALLATION.md
+++ /dev/null
@@ -1,6 +0,0 @@
-# Installation
-
-1. Upload the module to /protected/modules (or another module loader path) OR use `git clone https://github.com/felixhahnweilheim/humhub-flex-theme.git`
-2. Enable the module in Administration > Modules
-
-That's it! The theme is automatically activated.
diff --git a/helpers/ColorHelper.php b/helpers/ColorHelper.php
index 19d7083..3eddc95 100644
--- a/helpers/ColorHelper.php
+++ b/helpers/ColorHelper.php
@@ -2,11 +2,18 @@
 
 namespace humhub\modules\flexTheme\helpers;
 
+/**
+ * helper class for color manipulations, imitating the LESS functions lighten, darken, fade
+ */
 class ColorHelper
 {
     /*
-     * This function imitates the LESS function lighten()
-     * But it does not convert the color into HSL and back because this is not necessary to achieve the same result.
+     * lighten() imitates the LESS function lighten()
+     * It does not convert the color into HSL and back because this is not necessary to achieve the same result.
+     * @param string $color RGB hexadecimal color code including '#'
+     * @param int $amount between 0 and 100
+     * @param bool $relative wether to lighten relatively to ligthness, default: false
+     * @return string RGB hexadecimal color code including '#'
      */
     public static function lighten(string $color, int $amount, bool $relative = false): string
     {
@@ -16,16 +23,11 @@ public static function lighten(string $color, int $amount, bool $relative = fals
          */
         $color_parts = ColorHelper::getColorComponents($color);
 
-        // $amount is expected to be a number between 0 an 100
         $percentage = $amount / 100;
 
         // By default the LESS lighten() function adds the $amount absolutely to L, not relatively
         if (!$relative) {
-
-            /*
-             * Converting a RGB color to HSL, the Lightness would be calculated by L = [max(R,G,B) + min(R,G,B)] / (2 * 255)
-             * So we need $max and $min
-             */
+            //Converting a RGB color to HSL, the Lightness would be calculated by L = [max(R,G,B) + min(R,G,B)] / (2 * 255)
             $max = hexdec(max($color_parts));
             $min = hexdec(min($color_parts));
 
@@ -39,65 +41,78 @@ public static function lighten(string $color, int $amount, bool $relative = fals
             $percentage = $percentage / (1 - ($max + $min) / (2 * 255));
         }
 
-        $return = '#';
+        $result = '#';
 
         foreach ($color_parts as $color) {
             $color   = hexdec($color); // Convert to decimal
             $color   = round($color + (255 - $color) * $percentage); // Adjust color
             $color   = max(min($color, 255), 0); // keep between 0 and 255
-            $return .= str_pad(dechex($color), 2, '0', STR_PAD_LEFT); // Make two char hex code
+            $result .= str_pad(dechex($color), 2, '0', STR_PAD_LEFT); // Make two char hex code
         }
 
-        return $return;
-
+        return $result;
     }
 
     /*
-     * Documentation, see lighten()
+     * see lighten()
+     * @param string $color RGB hexadecimal color code including '#'
+     * @param int $amount between 0 and 100
+     * @param bool $relative wether to darken relatively to ligthness, default: false
+     * @return string RGB hexadecimal color code including '#'
      */
     public static function darken(string $color, int $amount, bool $relative = false): string
     {
-
-        $percentage = $amount / 100;
+        // split color into its components
         $color_parts = ColorHelper::getColorComponents($color);
-        $max = hexdec(max($color_parts));
-        $min = hexdec(min($color_parts));
-
-        if ($max == 0) {
-            return '#000000';
-        }
-
+        
+        $percentage = $amount / 100;
+        
+        // By default the LESS darken() function substracts the $amount absolutely to L, not relatively
         if (!$relative) {
-            $percentage = 2 * 255 * $percentage / ($max + $min);
+            //Converting a RGB color to HSL, the Lightness would be calculated by L = [max(R,G,B) + min(R,G,B)] / (2 * 255)
+            $max = hexdec(max($color_parts));
+            $min = hexdec(min($color_parts));
+            if ($max !== 0) {
+                $percentage = 2 * 255 * $percentage / ($max + $min);
+            }
         }
 
-        $return = '#';
+        $result = '#';
 
         foreach ($color_parts as $color) {
             $color   = hexdec($color); // Convert to decimal
             $color   = round($color * (1 - $percentage)); // Adjust color
             $color   = max(min($color, 255), 0); // keep between 0 and 255
-            $return .= str_pad(dechex($color), 2, '0', STR_PAD_LEFT); // Make two char hex code
+            $result .= str_pad(dechex($color), 2, '0', STR_PAD_LEFT); // Make two char hex code
         }
 
-        return $return;
-
+        return $result;
     }
 
+    /*
+     * fade() imitates the LESS function fade() which sets the opacity defined by $amount
+     * @param string $color RGB hexadecimal color code including '#'
+     * @param int $amount between 0 and 100
+     * @return string RGBA hexadecimal color code including '#'
+     */
     public static function fade(string $color, int $amount): string
     {
         // make sure we have 6 letters code not 3
         $color = '#' . self::getSixDigitsColor($color);
         
         // $amount is expected to be between 0 and 100
-        $opacity = ($amount / 100) * 255;
+        $opacity = round(($amount / 100) * 255);
         $opacity = max(min($opacity, 255), 0); // keep between 0 and 255
         $opacity = str_pad(dechex($opacity), 2, '0', STR_PAD_LEFT); // make 2 char hex code
 
-        // return RGBA as hex code
         return $color . $opacity;
     }
-
+    
+    /*
+     * Split color into its components (R, G, B)
+     * @param string $color RGB hexadecimal color code
+     * @return array color components as 2 character hexadecimal code
+     */
     protected static function getColorComponents(string $color): array
     {
         $hexstr = self::getSixDigitsColor($color);
diff --git a/helpers/FileHelper.php b/helpers/FileHelper.php
index 172d960..9fa3d3a 100644
--- a/helpers/FileHelper.php
+++ b/helpers/FileHelper.php
@@ -5,30 +5,18 @@
 use Yii;
 use yii\base\ErrorException;
 
+/*
+ * helper class for safely accessing and modifying files
+ */
 class FileHelper
 {
     public const THEME_PATH = '@flex-theme/themes/FlexTheme';
 
-    private static function getVarsFile(string $prefix)
-    {
-        return Yii::getAlias(self::THEME_PATH . '/css/' . $prefix . 'variables.css');
-    }
-
-    private static function getThemeFile(string $prefix)
-    {
-        if ($prefix === 'dark_') {
-            $fileName = 'dark';
-        } else {
-            $fileName = 'theme';
-        }
-        return Yii::getAlias(self::THEME_PATH . '/css/' . $fileName . '.css');
-    }
-
-    private static function getThemeBaseFile(string $prefix)
-    {
-        return Yii::getAlias(self::THEME_PATH . '/css/' . $prefix . 'theme_base.css');
-    }
-
+    /*
+     * Update the color variables CSS file with given content
+     * @param string $content
+     * @param string $prefix, empty for default file or 'dark_'
+     */
     public static function updateVarsFile(string $content, string $prefix): bool
     {
         try {
@@ -40,16 +28,16 @@ public static function updateVarsFile(string $content, string $prefix): bool
         return true;
     }
 
+    /*
+     * Reload the CSS and update the main theme CSS file
+     * @param string $prefix, empty for default file or 'dark_'
+     */
     public static function updateThemeFile(string $prefix): bool
     {
         // Base Theme
-        $theme_base = file_get_contents(self::getThemeBaseFile($prefix));
-
+        $content = file_get_contents(self::getThemeBaseFile($prefix));
         // CSS Variables
-        $vars = file_get_contents(self::getVarsFile($prefix));
-
-        // Create/Update theme.css
-        $content = $theme_base . $vars;
+        $content .= file_get_contents(self::getVarsFile($prefix));
 
         try {
             file_put_contents(self::getThemeFile($prefix), $content);
@@ -67,4 +55,24 @@ public static function updateThemeFile(string $prefix): bool
         }
         return true;
     }
+    
+    private static function getVarsFile(string $prefix): string
+    {
+        return Yii::getAlias(self::THEME_PATH . '/css/' . $prefix . 'variables.css');
+    }
+
+    private static function getThemeFile(string $prefix): string
+    {
+        if ($prefix === 'dark_') {
+            $fileName = 'dark';
+        } else {
+            $fileName = 'theme';
+        }
+        return Yii::getAlias(self::THEME_PATH . '/css/' . $fileName . '.css');
+    }
+
+    private static function getThemeBaseFile(string $prefix): string
+    {
+        return Yii::getAlias(self::THEME_PATH . '/css/' . $prefix . 'theme_base.css');
+    }
 }
diff --git a/models/Config.php b/models/Config.php
index 85cefb5..a8f39a9 100644
--- a/models/Config.php
+++ b/models/Config.php
@@ -26,7 +26,7 @@ class Config extends \yii\base\Model
     public $showTopicMenu;
     public $showUploadAsButtons;
 
-    public static function getSetting(string $setting_name): string
+    public static function getSetting(string $setting_name): ?string
     {
         // Note: return can be empty
         return Yii::$app->getModule('flex-theme')->settings->get($setting_name);
diff --git a/tests/codeception/acceptance/SettingsCest.php b/tests/codeception/acceptance/SettingsCest.php
index 03eee30..8ab873e 100644
--- a/tests/codeception/acceptance/SettingsCest.php
+++ b/tests/codeception/acceptance/SettingsCest.php
@@ -10,7 +10,7 @@ class SettingsCest
     public function testSettings(AcceptanceTester $I)
     {
         $I->amAdmin();
-        $I->amOnRoute(['/flex-theme/config']);
+        $I->amOnRoute(['/flex-theme/admin']);
         $I->waitForText('Flex Theme');
         $I->selectOption('#config-commentlink', 'icon');
         $I->selectOption('#config-likelink', 'icon');
@@ -22,7 +22,7 @@ public function testSettings(AcceptanceTester $I)
     public function testSettingsColor(AcceptanceTester $I)
     {
         $I->amAdmin();
-        $I->amOnRoute(['/flex-theme/config/colors']);
+        $I->amOnRoute(['/flex-theme/admin/colors']);
         $I->waitForText('Flex Theme');
         $I->jsClick('.form-collapsible-fields:nth-of-type(3) > div');
         $I->see('Background Color Page');
diff --git a/views/config/advanced.php b/views/admin/advanced.php
similarity index 100%
rename from views/config/advanced.php
rename to views/admin/advanced.php
diff --git a/views/config/colors.php b/views/admin/colors.php
similarity index 100%
rename from views/config/colors.php
rename to views/admin/colors.php
diff --git a/views/config/dark-colors.php b/views/admin/dark-colors.php
similarity index 100%
rename from views/config/dark-colors.php
rename to views/admin/dark-colors.php
diff --git a/views/config/index.php b/views/admin/index.php
similarity index 100%
rename from views/config/index.php
rename to views/admin/index.php
diff --git a/widgets/AdminMenu.php b/widgets/AdminMenu.php
index c91ba10..429d301 100644
--- a/widgets/AdminMenu.php
+++ b/widgets/AdminMenu.php
@@ -15,8 +15,6 @@
 
 /**
  * User Administration Menu
- *
- * @author Basti
  */
 class AdminMenu extends TabMenu
 {
@@ -27,9 +25,9 @@ public function init()
     {
         $this->addEntry(new MenuLink([
             'label' => Yii::t('FlexThemeModule.admin', 'General Settings'),
-            'url' => ['/flex-theme/config/index'],
+            'url' => ['/flex-theme/admin/index'],
             'sortOrder' => 100,
-            'isActive' => MenuLink::isActiveState('flex-theme', 'config', 'index'),
+            'isActive' => MenuLink::isActiveState('flex-theme', 'admin', 'index'),
             'isVisible' => Yii::$app->user->can([
                 ManageSettings::class
             ])
@@ -37,9 +35,9 @@ public function init()
 
         $this->addEntry(new MenuLink([
             'label' => Yii::t('FlexThemeModule.admin', 'Colors'),
-            'url' => ['/flex-theme/config/colors'],
+            'url' => ['/flex-theme/admin/colors'],
             'sortOrder' => 200,
-            'isActive' => MenuLink::isActiveState('flex-theme', 'config', 'colors'),
+            'isActive' => MenuLink::isActiveState('flex-theme', 'admin', 'colors'),
             'isVisible' => Yii::$app->user->can([
                 ManageSettings::class
             ])
@@ -47,9 +45,9 @@ public function init()
 
         $this->addEntry(new MenuLink([
             'label' => Yii::t('FlexThemeModule.admin', 'Dark Mode'),
-            'url' => ['/flex-theme/config/dark-colors'],
+            'url' => ['/flex-theme/admin/dark-colors'],
             'sortOrder' => 300,
-            'isActive' => MenuLink::isActiveState('flex-theme', 'config', 'dark-colors'),
+            'isActive' => MenuLink::isActiveState('flex-theme', 'admin', 'dark-colors'),
             'isVisible' => Yii::$app->user->can([
                 ManageSettings::class
             ])
@@ -57,9 +55,9 @@ public function init()
 
         $this->addEntry(new MenuLink([
             'label' => Yii::t('FlexThemeModule.admin', 'Advanced'),
-            'url' => ['/flex-theme/config/advanced'],
+            'url' => ['/flex-theme/admin/advanced'],
             'sortOrder' => 400,
-            'isActive' => MenuLink::isActiveState('flex-theme', 'config', 'advanced'),
+            'isActive' => MenuLink::isActiveState('flex-theme', 'admin', 'advanced'),
             'isVisible' => Yii::$app->user->can([
                 ManageSettings::class
             ])