Thimble, which is based on the Adobe-supported Brackets open source project, is still meant to be a platform for teaching the basics of web development. Mozilla is aiming the projects at educators (and their students) who want to build their own learning experiences, as well as at independent learners who want to teach themselves.
With this new version, Thimble is getting a new look with a choice of light and dark themes, a color picker and easier access to files and projects. Previously, you were also pretty much limited to a single project in Thimble. Now, you can manage and link multiple web pages.
Thimble now also reflects the fact that even beginners will want to target their sites at mobile, so the preview mode now allows you to see mobile previews as well. Other new features include support for importing zipped sites by simply dragging the files into the editor, autosave and support for extensions.