I have an existing app, which is almost two year old and I am planning to build new UI screens using bootstrap framework. I start to realize that new UI screens are NOT having the same look and feel. I don't think it is a good idea to release new UI features with a different UI look and feel. Is there any other approach to resolve this issue?

Couple of options:

  1. Rewrite the entire app using new UI Look and Feel: Huge cost issue.
  2. Follow old UI framework: Will never transition to new UI frameworks.

Any other option?

Many thanks in advance.

  • If this is a website isn't the look and feel specified by CSS, in which case you can edit the new CSS to make it look like the old site or edit the old CSS to make it look like the new stuff?
    – obelia
    Commented Mar 16, 2013 at 4:07
  • 1
    If you definitely want to introduce the new UI (for whatever reason), why not stage the release in two phases, the first would be to apply new UI to old screens, and if that works out well then apply them to the new screens. This will save you from having to revert to the old UI for new screens if things don't work out. You definitely should have consistent look and feel whether you are using new or old UI.
    – Michael Lai
    Commented Mar 17, 2013 at 23:40

3 Answers 3


Transition from old to new can and mostly is always hard because you need to justify the cost vs. benefit. And I totally agree with the consistency, not only in the look and feel but also in the way that elements behave in a website, ege. all datagrids should behave similarly.

You have to find a balance in between. You must have style-sheets and as a first step, you can updated the style-sheets to give a newer look and feel, which might not be dramatically different to the existing one. This means that when you apply the same css classes to similar elements in the website, you can add consistent behavior to them by the use of java script.

  • Thanks, yes, we started with an interim approach and it worked. Although they are two differnt framework so naturally they are NOT 100% same but they are close. Eventually, we will get rid of the old UI.
    – SyedA
    Commented Mar 18, 2013 at 22:24

What about:

  1. Know your users first. Which features are the most popular and what users are expecting from your app?
  2. Break down your UI into blocks (forms, fonts, modals, etc) regardless of the old/new features difference.
  3. Prioritize "new" UI framework implementation workload by balancing 1. and 2.

You are lucky because you can do this on your own schedule. When we have a new and look and feel that we want to fold into the application, we always have to do it piece-wise. This is because the application is just so huge that it is difficult to get through testing everything with a new look-and-feel in one release; and, because we did a poor job of initially separating the view from the data. I agree with other two answers that you should look at what features your users care about most of all, and tackle those first. Second, I would look at refactoring code as you go (a good principle of Agile design is to build in a certain amount of time each release into refactoring) to put more things into a view-controller like CSS. Then pushing the look-and-feel through the app.

Last, you should evaluate the purpose of the overhaul. Are you doing it for the big wow-factor? If so, branch the code and work on the look and feel for a big release. Or, are you doing it because the previous look-and-feel is creating a ton of usability problems? If so, pushing out piece-wise might make more sense.

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