The bootstrap 3 grid system targets 4 different screen resolutions, depending on their width:
I find that these resolutions do not represent the user group of my webapp. For example Medium and Small combined is used by less than 5 % of my user base (meaning less than 5 % of my users have a screen resolution width of 768px to 1199px).
I would rather target the following 4 different resolutions:
So I not only like to add an extra large set but also change / replace the medium, small and extra small one.
Has anybody run into similiar issues? I would love to use a grid generator where I input my custom grid widths and get out the CSS code.
You can customize pretty much every aspect of Bootstrap using the customization section of the official site.
http://getbootstrap.com/customize/#grid-system
That link takes you directly to the grid system items.
Enter your values, and download your custom version of Bootstrap. Even includes a JSON file with your settings so you can re-import them later and make adjustments.