Bug: blog post header img isn't optimized

[BekahHW]

Describe the bug

Right now, the blog post header image is off-centered. Ideally, we put in one image and it works for each post, but it would be useful to specify the size for each in sanity. Currently there's an option to put in a main img and social sharing post. So if we need four different sizes, we'll need to have inputs for each.

rel: #292

Steps to reproduce

1. go to opensauced.pizza/blog/
2. see the off-centered img

[favourachara07]

hey @BekahHW
is the main aim to resize the image