Before writing your own code, you should check the community. Emby has an active user base that creates and shares "skins."
Emby’s CSS customization system is a fantastic feature for power users who primarily use desktop browsers. However, its inability to reliably transfer those beautiful layouts to native TV and mobile applications holds it back from being a flawless skinning solution. Strengths & Weaknesses emby css themes
Adds a modern "frosted glass" effect to sidebars and overlays. Before writing your own code, you should check the community
layer that allows you to overhaul the look of the web client. By using the Custom CSS Before writing your own code
A: Yes, because the desktop app is essentially a web browser (Electron). Paste the CSS into the server dashboard, and the desktop app will reflect the changes.