Shopify Flooring Area Calculator

I need a small, well-structured block of Liquid and vanilla JavaScript added to the Dawn product page that lets shoppers type their room length and width (in metres), press nothing else, and immediately see:

• total square metres required, driven by an accurate, rock-solid m² formula (this calculation is the heart of the job)
• an optional 10 % wastage toggle presented as a smooth on/off switch
• the number of full packs they must buy, rounded up automatically because packs are sold in set sizes, with no extra choice or dropdown required
• the live product price adjusting as pack quantity changes, and that exact pack quantity flowing straight into the cart

Everything needs to look native inside the current Dawn layout, work flawlessly on mobile, and survive future theme updates. I’m only after clean, commented code—no third-party apps or bloated libraries.

Deliverables
– Liquid, CSS and JS snippets ready to paste into Dawn
– Clear installation notes (file names, line numbers, and how to reverse)
– Quick screen-capture or demo link proving mobile behaviour

Timeframe is three days and I’m offering a single fixed-price arrangement (no hourly quotes). When you reply, please include at least one Shopify project where you built comparable custom functionality without relying on apps; it will help me choose fast.