This is probably the way to go.
https://github.com/simov/simplr-smoothscroll
But you should be warned. People DON’T like when you scroll jack their browsing experience.
You should read more about it but there is a vocal majority that disliked using this technique.
You can read more about it on numerous blog posts. ex. http://www.sitepoint.com/scrolljacking-accessibility/ , http://blog.arronhunt.com/post/66973746030/stop-scrolljacking .
You should think really hard why you want to do this. There also a question about smartphone compatibility which can get really clunky.
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solved Adding Overall Smooth Scroll to a Website (Not for anchor links in the same page) [closed]