I've been asked to write a web application in PHP to handle customers, sales, estimates, invoices... I think I could benefit from a JavaScript library that could encapsulate some basic UI functionality (sortable listings, masked input fields, date pickers...) but I don't want to adopt a heavy framework that forces me to go through a steep learning curve and design my whole app around its API. I just want an unobtrusive enhancement.
jQuery is my library of choice for regular JavaScript tasks but I find that jQuery UI lacks important widgets/features and it's hard to style.
Do you have any suggestions?