Dynamic path for included/imported/linked files in XSLT (and other languages)

Hi. In my XSLT stylesheet I'm importing some CSS files. Given this code:

    <link href="themes/blank/styles/booking.css" rel="stylesheet" type="text/css"/>

I can click on the path-to-css-file and PHPStorm will take me to that file.

However, if I have something like

    <xsl:variable name="theme_path" select="'themes/blank'"/>
    <link href="{$theme_path}/styles/booking.css" rel="stylesheet" type="text/css"/>

PHPStorm, of course, can't get me to the file. Is there a way to config the look-up of the IDE and somehow define the `$theme_path` variable with a default value?

Thank you.