Container for adding code

Hi,

I have just added a loan calculator. For adding the code I used (I think) Spectra Shortcode in a container. I have had several problems with Spectra lately with styling. Now all text in the article under the block is bold. But not the paragraph above. When I remove the container with code, page is normal again.

The reason I used Spectra was TOC, but now Math Rank has one, so I am thinking stopping using Spectra since it gives me so much extra work and I also now can use Math Rank's TOC.

Is there another way to add the code [qis]? Or do you have any other good advice here?

The page in trouble:
Lånekalkulator