Informational Billing Email Template

I need a clean, reusable HTML email template to send billing-related information to customers. The focus is purely informational—no promotional content—so clarity, legibility, and flawless rendering across the major email clients (Gmail, Outlook, Apple Mail, Yahoo, mobile apps) are essential.

The template should be:
• Fully responsive and tested in both light and dark mode
• Built with inline CSS and a table-based structure so ESPs such as Mailchimp, SendGrid, and HubSpot keep all styling intact
• Accessible (ARIA labels, logical reading order, high-contrast color choices)
• Easy for my team to edit: clear comments, well-named sections for logo, account summary, due amount, and a prominent “Pay Now” CTA

Deliverables:
• Final, production-ready HTML file
• Brief style guide outlining fonts, colors, and editable regions
• Screenshots or a Litmus/Email on Acid test report showing successful rendering in the main clients

Please share examples of similar email templates you have coded so I can review quality and compatibility. I’m ready to get started as soon as I find the right fit.