The answer is in this case with ccs:
It depends a bit on what you exactly would like to make thinner. If you are using a table you can for example alter the padding of the table cells or rows. In the Variables.scss Mendix has by default the option to set the following:
//## Table spacing options (used in components/tables)
$padding-table-cell-top: 8px !default;
$padding-table-cell-bottom: 8px !default;
$padding-table-cell-left: 8px !default;
$padding-table-cell-right: 8px !default;
This will edit the padding for all tables used in your app.
You could also create a specific class for the table to be able to edit just this table. In this class you could edit: table.mx-table > tbody > tr > td
Finally using a lay-out grid and putting the input fields inside of it might be a better option.
Thanks for the response. I chose not to use the table widget because it has a lot of padding around it. I wanted to have more flexibility for spacing and alignment of the text boxes. Also I wanted to change the look of the textbox’s. So I end up using visual studio with Calypso. Modified the spacing for the label + text boxes, and then changed the look of the text boxes. It works quite well and I’m pretty much able to do what I want. By right clicking on the text boxes in chrome and then do an inspect I was able to do what I wanted.