diff --git a/src/Helpers/ColorConversion.php b/src/Helpers/ColorConversion.php
index e8242ee402eaa058e124241c4dbda8d4a13337d5..2be755f039299e8c3313f796c41046268502b1ff 100644
--- a/src/Helpers/ColorConversion.php
+++ b/src/Helpers/ColorConversion.php
@@ -11,7 +11,7 @@ class ColorConversion {
      *
      * @return bool  True if a light color.
      */
-    public static function is_hex_light( $color ) {
+    public static function is_hex_light( $color ): bool {
         $hex = str_replace( '#', '', $color );
 
         $c_r = hexdec( substr( $hex, 0, 2 ) );
@@ -31,11 +31,11 @@ class ColorConversion {
     /**
      * Convert RGB to HEX.
      *
-     * @param mixed $color Color.
+     * @param string $color Color.
      *
      * @return array
      */
-    public static function rgb_from_hex( $color ) {
+    public static function rgb_from_hex( string $color ): array {
         $color = str_replace( '#', '', $color );
         // Convert shorthand colors to full format, e.g. "FFF" -> "FFFFFF".
         $color = preg_replace( '~^(.)(.)(.)$~', '$1$1$2$2$3$3', $color );
@@ -52,17 +52,17 @@ class ColorConversion {
     /**
      * Make HEX color darker.
      *
-     * @param mixed $color  Color.
+     * @param string $color  Color.
      * @param int   $factor Darker factor.
      *                      Defaults to 30.
      *
      * @return string
      */
-    public static function hex_darker( $color, $factor = 30 ) {
+    public static function hex_darker( string $color, int $factor = 30 ): string {
         $base  = self::rgb_from_hex( $color );
         $color = '#';
 
-        foreach ( $base as $k => $v ) {
+        foreach ( $base as $v ) {
             $amount      = $v / 100;
             $amount      = self::round( $amount * $factor );
             $new_decimal = $v - $amount;
@@ -81,17 +81,17 @@ class ColorConversion {
     /**
      * Make HEX color lighter.
      *
-     * @param mixed $color  Color.
-     * @param int   $factor Lighter factor.
+     * @param string $color  Color.
+     * @param int    $factor Lighter factor.
      *                      Defaults to 30.
      *
      * @return string
      */
-    public static function hex_lighter( $color, $factor = 30 ) {
+    public static function hex_lighter( string $color, int $factor = 30 ): string {
         $base  = self::rgb_from_hex( $color );
         $color = '#';
 
-        foreach ( $base as $k => $v ) {
+        foreach ( $base as $v ) {
             $amount      = 255 - $v;
             $amount      = $amount / 100;
             $amount      = self::round( $amount * $factor );