Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Writer/Html.php
public function formatColor($pValue, $pFormat)
    {
        // Color information, e.g. [Red] is always at the beginning
        $color = null; // initialize
        $matches = [];

        $color_regex = '/^\\[[a-zA-Z]+\\]/';
        if (preg_match($color_regex, $pFormat, $matches)) {
            $color = str_replace(['[', ']'], '', $matches[0]);
            $color = strtolower($color);
        }

        // convert to PCDATA
        $value = htmlspecialchars($pValue);

        // color span tag
        if ($color !== null) {
            $value = '<span style="color:' . $color . '">' . $value . '</span>';
        }

        return $value;
    }
public function formatColor($pValue, $pFormat)
    {
        // Color information, e.g. [Red] is always at the beginning
        $color = null; // initialize
        $matches = [];

        $color_regex = '/^\\[[a-zA-Z]+\\]/';
        if (preg_match($color_regex, $pFormat, $matches)) {
            $color = str_replace(['[', ']'], '', $matches[0]);
            $color = strtolower($color);
        }

        // convert to PCDATA
        $value = htmlspecialchars($pValue);

        // color span tag
        if ($color !== null) {
            $value = '<span style="color:' . $color . '">' . $value . '</span>';
        }

        return $value;
    }
Add color to formatted string as inline style.

@param string $pValue Plain formatted value without color
@param string $pFormat Format code

@return string