PHP App for iPad/Mobile?

[TechnoBear]

Just a reminder that you already have answers to many of these questions:

Programming for an iPad

I have a potential customer who wants a way to do job estimation from his iPad. It would involved an estimation grid appearing - think like a pricing table/spreadsheet - and he could just tap on the appropriate cells in the grid to build an estimate. What would it require to build such a system? Could I just create a website that has “Responsive Design”, or would it require me building an App? Would I need to learn complicated things like Objective-C, MVC, OOP, etc? All I know is HTML, CSS,…