I am refreshing a long-running PHP website and need an experienced developer–designer to handle three tightly connected tasks: • Apply minor design updates: rethink some minor page layout issues and structure, alter some graphics and images, and leave the existing colour palette and fonts untouched. • Integrate new details for the same payment provider: I already have the gateway credentials ready; the current checkout flow must be rewired and tested end-to-end. • Revise the invoice template with the new company details. • Remove and amend some services and prices. The codebase is pure, procedural PHP with MySQL and a sprinkle of jQuery, so familiarity with those tools is important. The site is https://www.energycertscotland.com/. Please confirm you can work directly in the existing repository, outline how you would stage the changes, and include a quick note on similar legacy projects you have modernised.