diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yaml
similarity index 99%
rename from .github/workflows/ci.yml
rename to .github/workflows/ci.yaml
index 6fbf700..719716e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yaml
@@ -1,4 +1,4 @@
-# Inspired by Sebastian Bergmann's phpunit action workflow https://github.com/sebastianbergmann/phpunit/blob/main/.github/workflows/ci.yml
+# Inspired by Sebastian Bergmann's phpunit action workflow https://github.com/sebastianbergmann/phpunit/blob/main/.github/workflows/ci.yaml
 
 name: "CI"
 
diff --git a/src/Arguments/Option.php b/src/Arguments/Option.php
index 5602af4..332c514 100644
--- a/src/Arguments/Option.php
+++ b/src/Arguments/Option.php
@@ -46,7 +46,7 @@ public function verifiesType(mixed $value): bool
         };
     }
 
-    /** Returns the php property for the Arguments\Argument class */
+    /** Returns the PHP property for the Arguments\Argument class */
     public function getPhpProperty(): string
     {
         return match ($this) {
diff --git a/src/ProgressBar.php b/src/ProgressBar.php
index 8848a46..b664235 100644
--- a/src/ProgressBar.php
+++ b/src/ProgressBar.php
@@ -259,7 +259,7 @@ public function getCurrent(): int
     private function printTime(): void
     {
         // Time color by its total time
-        $time = Style::stylize($this->getFormattedTime($this->totalTime), fg: match (true) {
+        $time = Style::stylize(self::getFormattedTime($this->totalTime), fg: match (true) {
             $this->totalTime <= 500  => Foreground::GREEN,
             $this->totalTime <= 2000 => Foreground::YELLOW,
             default                  => Foreground::RED
@@ -267,7 +267,7 @@ private function printTime(): void
 
         // Allocated memory by its usage
         $memoryUsage = memory_get_usage(true);
-        $memory      = Style::stylize($this->getFormattedMemory($memoryUsage), fg: match (true) {
+        $memory      = Style::stylize(self::getFormattedMemory($memoryUsage), fg: match (true) {
             $memoryUsage <= 268435456  => Foreground::LIGHT_GREEN, // 256MB
             $memoryUsage <= 536870912  => Foreground::YELLOW, // 512MB
             default                    => Foreground::RED
diff --git a/src/Style.php b/src/Style.php
index 91ac0d6..a844bbf 100755
--- a/src/Style.php
+++ b/src/Style.php
@@ -7,6 +7,8 @@
 use function sprintf;
 use function get_class;
 use function preg_match_all;
+use function substr;
+use function trigger_error;
 use function get_called_class;
 use function str_replace;
 
@@ -24,9 +26,9 @@ class Style
      */
     public static function inline(
         string $string,
-        Style\Background $bg = null,
-        Style\Foreground $fg = null,
-        Style\Attribute $at = null
+        ?Style\Background $bg = null,
+        ?Style\Foreground $fg = null,
+        ?Style\Attribute $at = null
     ): void {
         print self::stylize($string, $bg, $fg, $at);
     }
@@ -36,9 +38,9 @@ public static function inline(
      */
     public static function outline(
         string $string,
-        Style\Background $bg = null,
-        Style\Foreground $fg = null,
-        Style\Attribute $at = null
+        ?Style\Background $bg = null,
+        ?Style\Foreground $fg = null,
+        ?Style\Attribute $at = null
     ): void {
         print self::stylize($string, $bg, $fg, $at) . PHP_EOL;
     }
@@ -202,9 +204,9 @@ public static function tag(string $tag): void
      */
     public static function stylize(
         string $string,
-        Style\Background $bg = null,
-        Style\Foreground $fg = null,
-        Style\Attribute $at = null
+        ?Style\Background $bg = null,
+        ?Style\Foreground $fg = null,
+        ?Style\Attribute $at = null
     ): string {
         if (!$bg && !$fg && !$at) {
             return $string;