Vanilla php + html5up + sqlite3. Everyone else here is trying to be stylish and fancy. Your customers don't care what language it's in or whether the code is beautiful. No cutting edge incomplete frameworks, convoluted tooling, piles of inaccurate documentation to read, inexplicable cryptic error messages with a bunch of incorrect solutions on stack overflow, or other incompetently over engineered bullshit. Just go a…
Also it is super flexible too (much like JavaScript and babel) as in you can write strict OOP code or you can write plain php code inside Html in static files.