SCSS extend a nested selector and override the nested rulesets

Question

Ok so I have a placeholder with a nested selector:

%block {
  .title {
    font-size:12px;
  }
}

I want to extend it and ADD to the .

Answer 1

You can use a tools, I used it to clean the css https://github.com/addyosmani/grunt-uncss

"A grunt task for removing unused CSS from your projects with UnCSS."