It seems that you did not install the gazebo, and as a result, bootstrap through the gazebo was not installed.
Install Bower
$ npm install -g bower
Install bootstrap through the gazebo
$ bower install bootstrap
You can learn more about this on the website. Also look for stand packages here . Since you are using angular, you can download angular-bootstrap.
UPDATE
What is bower provides a package manager for client modules. Like npm, with the difference that npm also provides backend- / nodejs modules.
If you use mean.io , your project will be prepared with a file called bower.json , and another with the name package.json , which defines the dependencies in your project. To install them, start by getting the node.js dependencies:
$ npm install
If you want the stand to be installed globally, use:
$ npm install -g bower
Then set the dependencies on the histogram
$ bower install
And now you should be good to go.
You can also add bower panel manually
or if you want to create your mean project from scratch
Install Bower
$ npm install -g bower
Install bootstrap through the gazebo
$ bower install bootstrap
Saving Dependencies
If you want to create bower.json to save dependencies:
$ bower init
and follow the instructions on the console.
Now that you are installing the new bower packages, you use --save and bower will add the dependency to your bower.json.
$ bower install bootstrap