Context for v3v3: Fix mobile horizontal overflow. The HTTP memo block used `.req .line { white-space: pre }` to preserve column alignment, but the longest line (`accept: text/agent-friendly, text/markdown, application/json`) forced the page wider than narrow viewports, which scroll-clipped the hero and nav on the left. Mobile media query now switches to `white-space: pre-wrap` + `overflow-wrap: anywhere` + 11.5px font — alignment preserved, no overflow at 320–430px.