If you want to use Bootstrap on your pen, go to the external stylesheets of the CSS section, type “Bootstrap” , select the option you want to use and include as many sources as you need! It truly is very simple to set up a pen.
Read moreHow do you add dependencies in CodePen?
#How to Add an External Resource Click the gear in the upper left corner of the JS or CSS editor . You’ll see the options pane for that editor. There is a text input where you can add the URL for your resource. If you don’t have a URL to add, you can use our resource search to find the library you need.
Read moreHow do I add a library to CodePen?
Or, click the “Settings” button in the header, then select the JavaScript tab from the Pen Settings menu.
Read more