how do i increase the padding within a thumbnail

Hello.

im struggling with finding a code to increase the gaps within a thumbnail. 

I tried using this according to a youtube video, but it doesnt work to me: 
#thumbnails{
    padding:  0 150px 0 150px;
}

What i like is to achieve more whitespace in between thumbnails with 3 in a row.

Thank you for you help.

https://ladybug-stingray-hdn2.squarespace.com/work

Can you share your website URL and where you are trying to increase the padding?

3 hours ago, Ziggy said:

Can you share your website URL and where you are trying to increase the padding?

Hi @Ziggy
that is my url
https://ladybug-stingray-hdn2.squarespace.com/work
thank you

2 minutes ago, LonniWong said:

that is my url
https://ladybug-stingray-hdn2.squarespace.com/work
thank you

Can you set up and share a site wide password so we can see the website?

https://support.squarespace.com/hc/en-us/articles/205815528-Site-wide-passwords

25 minutes ago, Ziggy said:

Can you set up and share a site wide password so we can see the website?

https://support.squarespace.com/hc/en-us/articles/205815528-Site-wide-passwords

ah sorry about that. Thank you.

i have set this now.

pw: test