Picking on your brain and hindsight ;) , and as someone who did little ES5 and DOM/browser API programming in the past, what would you recommend today for a fast track to a SPA for a solo project? (The learning process is not an issue). The interactivity is not very high but the UX can benefit from a SPA, is an invoicing system.

JS Framework, CSS methodology(UI framework?), etc... or any other perspective you want to share.