Reducing the padding on Flatiron blog pages?

Site URL: https://www.tamsinlouisephotography.com/journal

Hi, 

I've added a sidebar to left  of my blog in Flatiron template.  There was a lot of negative space here so I thought it would look quite nice.  However,  since doing this, rather than allowing the sidebar to fill this space, the padding has remained the same size and everything has just shifted over a little to the right. This looks fine but when I add the comments box, the box gets cut off, as well as my writing for the blog. Is there an option to reduce the space in-between the sidebar and the to left of my blog content? 

Here is a link to my blog pages on my website - https://www.tamsinlouisephotography.com/journal

Many thanks 🙂

Tamsin x 

https://www.tamsinlouisephotography.com/journal