blog: image captions

[elcaptain]

I see two problems with image captions:

1. They are the same style as normal body copy. At least, they should be in italics and closer to the image.
2. I don't think is the correct element for captions but .

[dan-long-dev]

@elcaptain - Here's a preview of an update caption style - https://deploy-preview-58--open-home-foundation.netlify.app/blog/building-whats-next-state-of-the-open-home-2026/

[elcaptain]

@dan-long-dev nice 👌 i would even make it italic to differentiate it even more