ZEN report - how to get bold header in displayxlsx $MODE

As stated, I have ZEN report, which I want to render in displayxlsx mode.

Currently it looks like this:

I want it to look like this:

Differences are:

• Bold header
• Cell width fitted to widest row or header

My report definition looks like this:

XData ReportDefinition [ XMLNamespace = "http://www.intersystems.com/zen/report/definition" ]
{
<report xmlns="http://www.intersystems.com/zen/report/definition"
 name="MyReport"
 sql="SELECT TOP 10 Name,DOB,Age FROM Sample.Person"
 runtimeMode="0">
  <group name="Person">
   <attribute name="name" field="Name"/>
   <attribute name="dob" field="Dob"
    expression="..ToExcelDate(%val)"/>
   <attribute name="age" field="Age"/>
  </group>
</report>
}

How can I get bold header and/or adequate cell width?