image size + design of calender sheet per day

I added the WP Advent plugin to my website which worked very well. Unfortunately, the image size of the calender is resized automatically by shortening the image on the left and the right side. I already tried several sizes but always get the same result.

Concerning the calender sheets per day, I found out that the complete design of my website is not displayed on these pages. It would be good to have the blog page on theses pages as well to keep viewers active within the blog.

Hope to get some ideas from you guys where to find the right settings within the plugin – thanks!

The page I need help with: [log in to see the link]