/* Responsive layer for the deployed demo. The design is desktop-first; below ~1150px its nav wraps to three rows and the hero's hard-coded 74px offset can no longer compensate, leaving a band of page background above the image. These rules fix the nav (two rows on tablet, a hamburger sheet on phones), the hero offset, and the chat launcher. Selectors are deliberately over-specific and use !important: the design's own