Stackline is an original fictional developer-platform study. The interactive stacked-layer hero is authored in CSS; hero.webp is an original code-drawn geometric illustration for the library thumbnail. No reference assets or source are reused. Geist, DM Serif Display, and Lucide licenses included. Design research: https://resend.com/ discovered through https://saaspo.com/pages/resend-landing-page . Reference page inspected for dark developer-product hierarchy, code tabs, test-mode examples and documentation flow. No real deployment or SDK is provided.