ChapmanCraftStudio

I've tried all of the codes I can find to change the blog title on the blog list page where each blog is previewed but the codes aren't working. I customized the date font but not the others. This is the one I found to customize the title that people seemed to have luck with but it's not working for me:

a.BlogList-item-title {
    font-family: 'casta-thin' !important;
}

Also need one for the read more nav....

I've attached an image of the blog preview on the blog list page: 

Site URL: https://polygon-oriole-cdcg.squarespace.com/

I'm using a custom font on this site but on mobile, the text overlaps itself. Why is this happening and what is the solution to this?? It's the h4 font that is having the error...

Here is my line of code for mobile font:

@media only screen and (max-width: 640px) 
{h1
{font-size: 30px;
  line-height:50px
}

  h4 {font-size:clamp(4px, 6vw, 10px);
   font-weight: 600;
  letter-spacing: .30em;
  line-height:.01px;
} }