diff --git a/src/Bootstrap4Alert.php b/src/Bootstrap4Alert.php
index c88ad77..b03f7d6 100644
--- a/src/Bootstrap4Alert.php
+++ b/src/Bootstrap4Alert.php
@@ -67,7 +67,7 @@ public function setBgStyle(string $color) : Bootstrap4Alert
      *
      * @return Bootstrap4Alert
      */
-    public function setHeading(string $heading, $heading_level = 4) : Bootstrap4Alert
+    public function setHeading(string $heading, int $heading_level = 4) : Bootstrap4Alert
     {
         $this->heading = $heading;
         $this->heading_level = $heading_level;
diff --git a/src/Bootstrap4Button.php b/src/Bootstrap4Button.php
index 015932e..7e73d56 100644
--- a/src/Bootstrap4Button.php
+++ b/src/Bootstrap4Button.php
@@ -92,7 +92,7 @@ public function __invoke(string $label): Bootstrap4Button
      *
      * @return Bootstrap4Button
      */
-    public function setBgStyle($color) : Bootstrap4Button
+    public function setBgStyle(string $color) : Bootstrap4Button
     {
         $this->assignBgStyle($color);
 
@@ -130,7 +130,7 @@ public function setOutlineStyle(string $style): Bootstrap4Button
      *
      * @return Bootstrap4Button
      */
-    public function setTextStyle($color) : Bootstrap4Button
+    public function setTextStyle(string $color) : Bootstrap4Button
     {
         $this->assignTextStyle($color);
 
diff --git a/src/Bootstrap4Card.php b/src/Bootstrap4Card.php
index 1082c8c..e8f377c 100644
--- a/src/Bootstrap4Card.php
+++ b/src/Bootstrap4Card.php
@@ -555,7 +555,7 @@ public function setHeader(string $content) : Bootstrap4Card
      *
      * @return Bootstrap4Card
      */
-    public function setBgStyle($color) : Bootstrap4Card
+    public function setBgStyle(string $color) : Bootstrap4Card
     {
         $this->assignBgStyle($color);
 
@@ -582,7 +582,7 @@ protected function assignBgStyle(string $color)
      *
      * @return Bootstrap4Card
      */
-    public function setTextStyle($color) : Bootstrap4Card
+    public function setTextStyle(string $color) : Bootstrap4Card
     {
         $this->assignTextStyle($color);
 
diff --git a/src/Bootstrap4Jumbotron.php b/src/Bootstrap4Jumbotron.php
index f6f121a..62d84fa 100644
--- a/src/Bootstrap4Jumbotron.php
+++ b/src/Bootstrap4Jumbotron.php
@@ -81,7 +81,7 @@ public function fluid() : Bootstrap4Jumbotron
      *
      * @return Bootstrap4Jumbotron
      */
-    public function setBgStyle($color) : Bootstrap4Jumbotron
+    public function setBgStyle(string $color) : Bootstrap4Jumbotron
     {
         $this->assignBgStyle($color);
 
@@ -112,7 +112,7 @@ public function setHeadingDisplayLevel(int $level) : Bootstrap4Jumbotron
      *
      * @return Bootstrap4Jumbotron
      */
-    public function setTextStyle($color) : Bootstrap4Jumbotron
+    public function setTextStyle(string $color) : Bootstrap4Jumbotron
     {
         $this->assignTextStyle($color);
 
diff --git a/src/Bootstrap4ProgressBarMultiple.php b/src/Bootstrap4ProgressBarMultiple.php
index 4adbbb4..3bb0508 100644
--- a/src/Bootstrap4ProgressBarMultiple.php
+++ b/src/Bootstrap4ProgressBarMultiple.php
@@ -180,7 +180,6 @@ private function reset(): void
         $this->bg_colors = [];
         $this->striped = false;
         $this->animate = false;
-        $this->label = null;
         $this->height = null;
     }