It appears New-HTMLTableHeader has the FontSize 0 Bug

If you do not specify -FontSize while using New-HTMLTableHeader the header will not be shown.

```
$tmp1 = @"
Job State,Count
DONE,5035
ACTIVE,24
"@ | ConvertFrom-Csv


New-HTML -Temporary -ShowHTML {

  New-HTMLTable -DataTable $tmp1 {

    New-HTMLTableHeader -Names 'Job State' 
    New-HTMLTableHeader -Names 'Count' -FontSize 12

  }

}
```

