Decrease opacity for blog post headers in all posts

Hey there,

Amazing theme – I’m loving it so much and my blog looks so much more vibrant with it, so thank you! I have a question:

How can I reduce the opacity for the dark overlay on top of the blog post headers in the all posts page? Here is my blog for reference: https://otherworld.ly

As you can see, the home page is the all posts page, and all of the overlays are quite dark. I’ve tried changing it in the Theme Options as well as searching around the forums for the answer to this question, but to no avail. Any help would be amazing!

Thank you,
Jen