How to reduce space between different text styles in one text block

Hello all, 

I'd like to change text spacing for only specific text blocks and not the entire website.
I found a thread from 2017 where the recommendation was for 

p {
 margin-top: 0;
}

When I add it with the block ID it changed the entire page (and assuming the entire site).  
I could be putting it in wrong but didn't know if there was another way to add it? 

Here's the link

www.emiesphoto.com

Ones I'd like to do specifically are the blocks beside my photos on this page.  I'm wanting to change the layout but keep the blocks like this and utilize h1 h2 h3 and p but keep them closer 

https://emiesphoto.com/services

Try

#enter-text-block-id p {
 margin-top: 0;
}

Use this tool to find text block id https://chrome.google.com/webstore/detail/squarespace-id-finder/igjamfnifnkmecjidfbdipieoaeghcff?hl=en