Email Theme for Ecommerce Website

I need a clean, responsive HTML email theme that showcases our ecommerce promotions first and foremost, wrapped in a bold, vibrant aesthetic that fits a modern retail brand. The template has to render flawlessly in Gmail, Outlook, Apple Mail, Yahoo, and the usual mobile apps, so solid experience with the quirks of every major email client is essential.

Scope of work
• Design a master template plus modular blocks I can mix and match: hero promotions, product grids, banners, and offer highlights.
• Build the code from scratch—no builders—using lightweight, well-commented HTML and inline CSS that meets best-practice deliverability standards.
• Integrate three must-have features out of the box: a live-update countdown timer for limited-time deals, social media icons that match the colour palette, and a compact customer testimonial section.
• Optimise every element for fast loading, retina displays, and easy text/image swaps by my in-house team.

Acceptance criteria
– Pixel-perfect on the latest Litmus or Email on Acid tests across 40+ clients/devices.
– Fully responsive down to 320 px width with no horizontal scrolling.
– Images, buttons, and mixed-content sections pass Gmail dark-mode checks.
– Delivered as a single HTML file plus a brief hand-off guide explaining layer order, content limits, and how to update timer scripts.

If you have live examples of ecommerce emails you coded that balance bold design with technical reliability, include them in your reply—those will help me move quickly on long-term collaboration.