I find for my projects that the fuzzy finder overlay dialog in the Atom editor is a little short for my liking. I often have long path names with the same file name so I and can't see the full path, therefore I am not sure which file I am choosing.

Atom fuzzy finder original size

The easiest way to do this is to use your custom stylesheet to alter the fuzzy finder interface. Open your Atom stylesheet via the menu options Atom -> Open Your Stylehseet.

Next paste in the following CSS code. Save the file and the Atom styles will automatically reload.

.modal.overlay {
  width: 800px;
  margin-left: -400px;
}

.fuzzy-finder {
  width: 784px;
}

Open the finder again and now it looks much better!

Atom fuzzy finder after width customisation

Of course you may want to customise the widths of the modal to fit your workspace better.