Feature Request: Styling (theme modes) for better customization and custom themes

I’d love to see ChatGPT support custom themes and UI personalization.

Right now, customization is limited, but imagine if users could:

• Create and apply pre-set themes (switchable in settings)
• Build fully custom themes using code (CSS-like or a safe theme language)
• Share themes with the community (like plugins or presets or a sharable link
• Toggle themes per conversation or global settings

This would open the door for a much more personal experience - everything from minimal dark setups to highly stylized creative UIs.

Curious what others think: Would you use custom-coded themes, or prefer ready-made presets? And what kind of theme system would feel most usable to you?