Shopify Product Page Layout Customization

I need my current Shopify product template re-worked into a clean, custom layout. The new page must present all product variables clearly, include a smooth quantity selector, highlight a “Subscribe & Save” option, and keep the Add to Cart button instantly visible.

Key changes I expect:
• Custom arrangement for the product-variable picker so shoppers can choose size, color, or other variants without extra clicks
• A quantity input that is easy to adjust on both desktop and mobile
• A prominent Subscribe & Save toggle (recurring orders) placed next to the price
• The Add to Cart button fixed in the flow so it never slips below the fold

Should be liquid-responsive, clean, and documented well enough for my in-house team to tweak later. I should be able to easily edit each one with shopify's editor.

Example for desktop and mobile view attached.