если кому-то это просто нужно.
Вот шаги:
1. Npm install bootstrap@3.3.7
2. Change the bootstrap entry from package.json and replace it with "bootstrap": "3.3.7"
3. in resources/assets/sass/app.scss,
a. comment out the import of variables
OR change height base to 14 px instead of 0.9 rem in _variable.scss.
b. change the path of bootstrap to
@import "node_modules/bootstrap-sass/assets/stylesheets/bootstrap";
4. in resources/assets/js/bootstrap.js,
look for require('bootsrap-sass'); and change it to require('bootstrap');
Надеюсь, это поможет!