Customer portal 'design mode'

[JJack]

Hi,

I'm adding a new tile to one of our main self-service pages.
We currently have a number of rows with five tiles each, which is enough for the width of the page at a fairly standard zoom level.

If I add a new row that just has one link/tile in it, it sizes itself differently, ending up a bigger box than the rows above. Even if I remove the border, it's still obviously bigger.

There are four blue things that appear if I hover over the relevant Links section, and the single tile will move further to the right the more of these I select -

I can't see any way to affect the size of the tiles, can anyone advise?

Thanks.