Ggtcf

I have this XSLT

<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output encoding="iso-8859-1" method="html"/>
 <xsl:template match="/">
 <img src='http://www.acentroservices.it/wp-content/uploads/2018/02/document.jpg' style="border: 1px solid black"/>
 <style>
 img 
 width: 100%
 
 </style>
 <xsl:if test="count(list/*) &gt; 0">
 <h2>Ci sono <xsl:value-of select="count(list/element)" /> elementi!</h2>
 </xsl:if>
 <xsl:if test="count(list/*) = 0">
 <h2>Niente!</h2>
 </xsl:if>
 </xsl:template>
</xsl:stylesheet>

That I use to transform this XML

<list><element><id>2</id><uuid>96506f09-eb04-46a2-af86-42fe9c6767ce</uuid><langcode>it</langcode><type>stu_pratica</type><user_id>1</user_id><name>a</name><status>1</status><created>1552053309</created><changed>1552053331</changed><unique_key>a</unique_key><users>admin</users><xml_content></xml_content><default_langcode>1</default_langcode><field_stu_pratica_classe_proc></field_stu_pratica_classe_proc><field_stu_pratica_data_atto></field_stu_pratica_data_atto><field_stu_pratica_data_fine></field_stu_pratica_data_fine><field_stu_pratica_data_inizio></field_stu_pratica_data_inizio><field_stu_pratica_d_protocollo></field_stu_pratica_d_protocollo><field_stu_pratica_ente></field_stu_pratica_ente><field_stu_pratica_esito></field_stu_pratica_esito><field_stu_pratica_indirizzo></field_stu_pratica_indirizzo><field_stu_pratica_lat></field_stu_pratica_lat><field_stu_pratica_lon></field_stu_pratica_lon><field_stu_pratica_nome_proc></field_stu_pratica_nome_proc><field_stu_pratica_num_atto></field_stu_pratica_num_atto><field_stu_pratica_n_protocollo></field_stu_pratica_n_protocollo><field_stu_pratica_primo_int></field_stu_pratica_primo_int><field_stu_pratica_resp_unico></field_stu_pratica_resp_unico><field_stu_pratica_stato></field_stu_pratica_stato><field_stu_pratica_wkid></field_stu_pratica_wkid><field_stu_pratica_x></field_stu_pratica_x><field_stu_pratica_y></field_stu_pratica_y></element></list>

But, in any way I try to execute the transformation:
- style attribute is stripped from every possible tag
- style tag is removed, but it's content is not

This happens only in PHP XSLTProcessor, any online tool I used kept the CSS instructions.

How do I keep CSS instructions in the output?
Why does this happen only in PHP XSLTProcessor and not in the online tools?

Thanks everybody for the help.

EDIT:

That's the piece of PHP code I'm using to operate the transformation:

 $output = new DOMDocument();
 $output->loadXML(utf8_encode($body)); // For the XML 

 $xslt = new XSLTProcessor();
 $xsl = new DOMDocument(); // For the XSLT Template

 $xsl->load($xslt_path, LIBXML_NOCDATA);
 $xsl->formatOutput = TRUE;
 $xslt->importStylesheet($xsl);
// Setting some parameters, shouldn't have to do with the css problems i think... 
 $xslt->setParameter('', 'base_url', $base_url);
 $auth_url = Url::fromRoute('stu_botfo.view_authenticated_element', ['bundle' => $bundle, 'id' => ''], ['absolute' => TRUE]);
 $xslt->setParameter('', 'view_authenticated_element_link', $auth_url->toString() . '/');
 $anon_url = Url::fromRoute('stu_botfo.view_anonymous_element', ['bundle' => $bundle, 'id' => ''], ['absolute' => TRUE]);
 $xslt->setParameter('', 'view_anonymous_element_link', $anon_url->toString() . '/');
 $xslt->setParameter('', 'map_url', $map_url);
 return $xslt->transformToXML($output);

Solved, thanks a lot everybody.
Turns out it was not XSLTProcessor fault, but some HTML filter I was not aware of that took place later in the rendering process, I'm really sorry for not thinking about it before.

In most cases if you expect HTML as output you better use transformToXML() directly in the PHP XSLTProcessor. You gain better control over xsl:output attributes.

I am not sure if you are directly calling transformToDoc() in the PHP code.