Why doesn't negative margin work?

Question

css

There is a common ul container with a width of 1170px. Each item takes up 370px and 30px of padding to the right. To accommodate three items, I put a negative margin -30px on the common container, but nothing works. box-sizing: border-box is. Tell me, what's the problem?

Answer 1

It is necessary not to put a negative margin on the common block, but to remove the right indent from the item, every third
Type has something like this

Answer 2

The screenshot does not give an idea of ​​​​the problem at all, users of the toaster for psychics, do not forget about it.
Negative padding works crookedly on those elements that have a width value other than "width: auto;"
If your ul is set to something like "width: 100%" or "max-width: 100%", try changing it to auto.
Or the problem is something else, you need to look directly at the code.
PS In general, JorJeG wrote everything correctly: solving a similar problem through a negative indent is a crutch, and very unpredictable at that. It would be more correct to solve this problem through pseudo-classes, such as :nth-child