core-bundle/src/Resources/contao/classes/StyleSheets.php
protected function shortenHexColor($color)
	{
		if ($color[0] == $color[1] && $color[2] == $color[3] && $color[4] == $color[5])
		{
			return $color[0] . $color[2] . $color[4];
		}

		return $color;
	}
protected function shortenHexColor($color)
	{
		if ($color[0] == $color[1] && $color[2] == $color[3] && $color[4] == $color[5])
		{
			return $color[0] . $color[2] . $color[4];
		}

		return $color;
	}
Try to shorten a hex color

@param string $color

@return string