### Description It would be nice if we can enable a customizable line limit most IDEs have, especially while viewing merge requests. ### Problem to solve With the current way the diff view is displayed, when you're working on projects that have a conventional line limit to be enforced, there is no way on the diff view to see whether lines go beyond that limit ### Proposal Tested on Firefox 55.0: I managed to do something similar using Firebug, by adding the following CSS rule. ```css .line_content::after { border-right: 1px solid rgba(255, 0, 0, 0.5); content: ""; left: 80ch; position: absolute; top: 0; padding-left: inherit; } ``` The rule uses the [ch](https://developer.mozilla.org/en/docs/Web/CSS/length#ch) unit to position the border 80 characters to the right. It also inherits the padding from its parent to take into account the `+`, `-` or space character that pads the lines slightly to the right. ### Screenshot I took a random Merge Request (12934) from the repo here and added the previous CSS in the browser inspector. I also edited one of the lines so it includes numbers from start to end, so it wraps to the next line.  ### Links / references 1. Browser support for ch on MDN: https://developer.mozilla.org/en/docs/Web/CSS/length#compat-desktop 2. Browser support for ch on "Can I use": http://caniuse.com/#search=ch