WordPress blog post appearing to be centralized

I recommend asking at https://www.ads-software.com/support/theme/ribbon-lite so the theme’s developers and support community can help you with this.

It’s the <center> tag that made the content align center.
This is what I would advice.

Replace <center> with <div>, or
Add a css to this class “post-content”, text-align:left;

This should solve your problem.

in your root style.css past

.post.excerpt {text-align:left;}

it will resolve your issue

Thanks