Plinth is a single-file HTML/CSS/JS template for interior design and boutique consultancy brands — no framework, no build step, no dependencies. Ships with a CSS-only 3D "material sample" hero scene, an art-directed dark mode, four hand-built CSS portfolio compositions instead of stock photos, a validated contact form, and a keyboard-accessible flip card. Built by a freelance dev with 3+ years and 40+ shipped sites.