/* ============================================ HOMEPAGE FEATURE 4 — Liquid Glass Navigation FAB Floating frosted-glass button in bottom-right. Expands to show section links with a glass effect. ARCHITECTURE: - Fixed-position FAB in bottom-right corner - Expands to frosted-glass section-picker menu - Active section tracking via IntersectionObserver - Upload button + section links + external links DEPENDENCIES: - homepage-feature-4-liquid-glass-navigation.html (fragment) - homepage-feature-4-liquid-glass-navigation.js (loads fragment) - CSS custom properties from homepage.css - Font Awesome (icons, loaded by homepage.html) LOAD STRATEGY: - CSS linked in homepage.html (avoids FOUC) - JS loaded via