excerpt/content formtting problem

I am trying to get a blog to show full posts on the front page but when I do it causes formatting problems that I cant seem to fix. I can get it to show full posts on the front page by changing-

<?php the_excerpt(__('keep reading', 'grisaille')); ?></div>
to
<?php the_content(); ?>
in the ‘home.php’ file.

This does allow me to show full posts but it changes the formatting of the page entirely. I tried to show the difference between the two by posting how it should look in a post ‘how it should look’ on the front page:

https://www.thevintagenotebook.com

Can anyone tell me how I can bring the secondary menu back up to the top right and how to stop the top post outline expanding all the way down and around all the posts?

Hope this makes sense