5.1 items placed into the <head> element of the template were rendered after stylesheets that were added via the @Import. This meant you could add code or style sheets that would override the stylesheets added by @Import. As of 5.2 it appears that this has changed and now the @Import style sheets show up AFTER items that are added in the <head>. This means there isn't a way to override the stylesheets by adding <style> to the <head> element.
Here is an example of what is occurring in 5.2.2
<meta http-equiv="content-type" content="text/html; charset=utf-8"/>
Is rendered as:
<meta content="text/html; charset=utf-8" http-equiv="content-type"></meta>
<link type="text/css" rel="stylesheet" href="/register/assets/1.0-SNAPSHOT/tapestry/default.css"></link>
<link type="text/css" rel="stylesheet" href="/register/assets/1.0-SNAPSHOT/ctx/layout/layout.css"></link>
<meta content="Apache Tapestry Framework (version 5.2.2-SNAPSHOT)" name="generator"></meta>