How can I increase cell width or space three cells across full page

Please try adding the following code to your form as shown on this guide: https://www.jotform.com/help/117-How-to-Inject-Custom-CSS-Codes 

#id_249,#id_104{

    margin-right: 8% !important;

}

#id_254,#id_277,#id_89,#id_44 {

    margin-right: 11%;

}

#id_85,#id_75{

    margin-right: 15%;

}

#id_278,#id_279{

    margin-right: 12%;

}

#id_74,#id_77 {

    margin-right: 13%;

}

#id_274,#id_270{

    margin-right: 13%;

}

#id_315,#id_283{

    margin-right: 14%;

}

#id_318,#id_310{

    margin-right: 6%;

}

Result: https://form.jotform.com/80307353026953

Hi, thanks for the codes below which worked.
I ‘ve added a new section below in the same form. Could I get the column width codes for this one as well please.
Thanks
Funda
...

Hello Funda - Are you referring to this misaligned section?

If so, modify the last section of the codes given by David.

FROM:

#id_318,#id_310{

    margin-right: 6%;

}

TO:

#id_318, #id_310 {

    margin-right: 14%;

}

If you're referring to a different section of your form, please tell us exactly which needs to be adjusted so we can provide you the codes you need. In case you're planning to share a screenshot of it, don't reply to this email.

Instead, kidnly post it directly to your thread https://www.jotform.com/answers/1368848

Complete guide: How-to-Post-Screenshots-to-Our-Support-Forum

Hi, tried that formula but it didn’t. area you highlighted below is still as it is.
Could you take another look please
Thanks
Funda
...

You had a missing closing bracket in the CSS code:

I added it and it should be fine now.

Let us know if you have any further questions.

Thank you!