Table setColumnAlignment makes header vanish

I have a two column table (description, amount) which displays the header and body just fine.
But I want the amount to be right justified so I do this:

setColumnAlignment(amountColumn, Table.ALIGN_RIGHT);

And that works perfectly for the body, but the header text disappears.
I can see the text is still there when I look at the resulting page with Firebug, so this must be a style thing.
When I click on the (empty) amount header it comes right, when I click on the (now okay) description header it goes bad again.
Clicking does sort things okay, which is good. The sort arrow vanishes with the header text.

This is the generated html I can see in firebug for the description header:

<td class="v-table-header-cell" style="width: 308px; ">
<div class="v-table-resizer"/>
<div class="v-table-sort-indicator"/>
<div class="v-table-caption-container" style="width: 299px; ">Description</div>

My style.css extends runo but doesn’t have an entry for any of the classes mentioned there.

I think I can see a trace of the ‘Description’ caption along the bottom of the cell, there’s some hard-to-see rubbish there which might be the high bits of the word.
No equivalent on the Amount column though. I tried to attach screen images to show this, but it didn’t like my png files (although it says they are one of the valid types)
I’m using Vaadin 6.6.6, browser is Chrome, but it does the same on FF.

Thanks for your help.

The problem was in the style definition. I added this

and it works fine now. I think the critical setting is the padding. The inherited setting had something quite odd.