Explanation : Bootstrap has a responsive layout. In the preview window there is no space for three columns, but when you do a full-screen preview, all columns suddenly fit.
Please re-edit your Post
Your code will then be in a pre-code stateand you will be able to make/present the proper indentations.
or even better use= http://discuss.codecademy.com/t/using-backticks-to-format-your-code/3697/2[extra's]https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet