Deprecation: #95349 - TypoScript: page.includeCSS/includeCSSLibs.import

See Issue #95349

Description

The option to use the @import syntax for including external CSS files through TypoScript has been marked as deprecated.

This was possible through:

page = PAGE
page.includeCSSLibs.file1 = fileadmin/benni.css
page.includeCSSLibs.file1.import = 1

Through the “import = 1” option the output was

<style>
    @import url('fileadmin/benni.css');
</style>

Impact

A PHP E_USER_DEPRECATED error is triggered when having the import = 1 flag enabled in TypoScript on includeCSS or includeCSSLibs properties.

Affected installations

TYPO3 installations with the TypoScript settings

page.includeCSS.aFile.import = 1 page.includeCSSLibs.aFile.import = 1

enabled are affected.

Migration

Using the <link> tag syntax, which is the de-facto standard syntax these days, allows to load a file directly when interpreting the HTML of the browser, instead of first interpreting the HTML, then the CSS and have a blocking call to an external URL to continue interpreting the CSS.

It is recommended to use the <link> tag or create a inlineCSS TypoScript manually to load such a file with the @import syntax.