Hey , unfortunatly it's not possible but you can trick it as this
in items you can write smthng like this :
<h3>header1</h3>:text:text:text;
<h3>header2</h3>:text:text:text;
<h3>header3</h3>:text:text:text;
<h3>header4</h3>:text:text:text;
<h3>header5</h3>:text:text:text;
<h3>header6</h3>:text:text:text;
<h3>header7</h3>:text:text:text;
<h3>header8</h3>:text:text:text;
h3 is a header balise , that will change that cell's fonts so it will appears as a non-normal cell
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