JD Builder is based on basic Grid system and flexbox, which by default has a column width of 12 and you can NOT have 5, 7, 9, 10 or 11 columns in a row. But it’s possible with a little bit of CSS help.
The Idea is to have 1 column in the row and drop your content vertical but use CSS to list the individual items horizontal and automatically adjust for equal width.
Adding the following CSS on column level would do just the same:
.jdb-element { display: flex; justify-content: center; align-self: center; }
Once done, all your elements will automatically be adjusted and listed vertically.