title: How to customize bootstrap css when using bootstrap-sass
body: <p>I'd like to change many things, for example buttons color or for example change the background-image color on the nav bar (header).
  I use boostrap-sass gem so i can't use boostrap website' <a href="http://twitter.github.io/bootstrap/customize.html" rel="noreferrer">Customize page</a></p>
  
  <p>Should I really override all these on my file custom.css.scss or can I change these somewhere more low level ?
  i don't find the .css files allowing me to do that in my project file (I searched all lib, app and vendor /assets but noweher i find the css of boostrap. i suspect it's because they're not there but they're directly in the gem files)
  I have a lot of changes so i feel overiding so many things is not the best option.</p>
  
  <p>What's the best way to do this?
  Thanks</p>