Fix Step-Based Booking Buttons

I’m putting the finishing touches on a three-step service booking flow using plain HTML, CSS, and a little vanilla JavaScript. At the moment the “Continue” button loads in its disabled state and never flips to enabled, so users get stuck on the first screen. I also need the radio selection and the final “Pay Now” button to carry the visitor smoothly through all three steps and close the booking.

You’ll receive my current markup and scripts; no frameworks or build tools are involved. Your job is to tidy the DOM events, make the Continue button toggle predictably when required fields are met, preserve the chosen radio option across steps, and ensure the Pay Now button completes the flow with a success message.

Acceptance criteria
1. Continue button enables/disables correctly and moves to step 2.
2. Selected radio value persists into the summary.
3. Pay Now finishes step 3 and confirms the service booking.

Return the updated HTML/JS files and a short changelog so I can see what you tweaked. Looking forward to wrapping this up quickly!