A while a GitHub issue in the sp-dev-docs came to my attention, where someone had a problem titled as Can’t get grid system working using office fabric ui react. I took a closer look on why it is so challenging to get the grid system running right now and in SPFx projects in general. There are some catches you need to be aware.
Some of those issues are already documented in the a blog post on How to make your web parts responsive to the parent container or How to use Bootstrap in SharePoint Framework projects. Here is the rest of the story.
Office UI Fabric is somewhat like the first and foremost first third-party Framework that you may want to use in all your projects to create a seamless experience with the rest of the Office 365 platform. It is not exclusively to SharePoint or SharePoint Framework Projects.