The margins you’ve set here appear to be with the aim of getting the 3 <div>'s you’ve created to appear as if they’re in a single row (as if in a table-like structure). Is that an accurate interpretation of what you wish to do? If so, it’s a very poor technique to use to meet the end goal.
You’d be far better off using a combination of display: table;, display: table-row;, and display: table-cell; and to forget about using negative margins as a positioning tool - that’s not what they’re for.
The idea here is that we help you learn how to do this for yourself. I know that you’ve been shown how to make use of the display property to create layouts that simulate the appearance of a table on more than one occasion. I’d suggest you review those first, as well as the link I’ve provided above, then give it a go yourself.
To the best of my knowledge, it’s only really used when you want to hide a page element outside the visible area of the viewport, but someone with more experience than myself, can probably give you a better response.
Not seen that one yet - do you think I should?
Have you changed the code again? That is not what I looked at when I offered my original suggestion.
That is not accurate. There is a 5 minute grace period after a post is initially saved during which it can be edited without leaving a trace. I thought the code was different, too, but don’t remember whether it was the code in the fiddle or the code in the post.