What's the best method to handle this issue?

Hey there.
So I am currently struggling to find a nice solution for my kind of problem.
In the contact form, I need the user to be able to firstly select between 3 options (also multiple selections) and then in another checkbox select between 20 options, also, multiple selections should be possible.
Now, I know how to set it up, but apparently I am doing something wrong, since each option appears in a new row, resulting in the contact form to be really long and ugly.

The person I’m doing that for does now want a drop-down menu.

Here I show you what I have:

I’d need it prettier..maybe in two rows ??

Can anybody help me out here? Really not understanding how to do that, I already read in the FAQ Section about styling, whilst I am able to style the rest of the form, I really don’t get the checkbox to work.

Here’s the relevant code:

Sie sind...* [checkbox* menu class:ueber-sie multiple "Unternehmer" "Immobilienbesitzer" "Privatperson"]
<div class="column-full">Weitere Angaben*(mehrere m?glich) [checkbox* ueber-sie-optionen multiple id:ueber-sie-optionen
"aktiv selbstst?ndig" "Mitarbeiter besch?ftigt" "Vollstreckungsma?nahmen eingeleitet" "Steuerschulden vorhanden" "Steuerstrafverfahren eingeleitet" "Schulden bei der Krankenkasse" "Ich bin Immobilienbesitzer" "Kredit gekündigt" "Zwangsversteigerung beantragt" "gekündigt Zwangsversteigerung" "arbeitssuchend" "Besch?ftigungsverh?ltnis" "Kontopf?ndung" "Lohnpf?ndung" "Unterhaltsschulden"]

https://www.ads-software.com/plugins/contact-form-7/