Using or within html select option

I'm trying to style the inside of a select option. This is the code I'm using to display the various parts of results from my sql query ...

echo '<option value="'.$colour_id.'">'.$range_name.' - '.$colour.$plank_display.$code_display.'</option>';

I am trying to show $colour & $plank_display in bold/strong

I have tried ..

echo '<option value="'.$colour_id.'">'.$range_name.' - <span style="font-weight: bold;">'.$colour.$plank_display.'</span>'.$code_display.'</option>';

and ...

echo '<option value="'.$colour_id.'">'.$range_name.' - <strong>'.$colour.$plank_display.'</strong>'.$code_display.'</option>';

but neither seem to be yielding the results I am looking for.

There is no other styling applied to the form, neither is there even a stylesheet attached to the page yet.

Any ideas? Or am I going about this in the wrong way.

I can apply styling to the option to make the whole line bold using css in a style sheet, but I just want this specific bit to stand out.

via Chebli Mohamed