Customize title hl group background

Is there any way to set custom highlight groups for the different titles ("ChatGPT", "Prompt", "System", etc.)? I'm trying to configure the windows to match my telescope theme exactly, and this is the last hurdle in the way. Thanks.

Telescope Theme


ChatGPT Theme


Current Configuration

```lua
opts = {
popup_window = {
border = {
highlight = "TelescopePreviewBorder",
},
win_options = {
winhighlight = "Normal:TelescopePreviewNormal,FloatBorder:FloatBorder",
},
},
system_window = {
border = {
highlight = "TelescopePromptBorder",
},
win_options = {
winhighlight = "Normal:TelescopePromptNormal,FloatBorder:FloatBorder",
},
},
popup_input = {
border = {
highlight = "TelescopePromptBorder",
},
win_options = {
winhighlight = "Normal:TelescopePromptNormal,FloatBorder:FloatBorder",
},
},
settings_window = {
win_options = {
winhighlight = "Normal:TelescopePromptNormal,FloatBorder:FloatBorder",
},
},
},

```

The issue names no implementation files or tests. Start by tracing the plugin's window and title highlight configuration, using the supplied popup_window, system_window, popup_input, and settings_window options as the configuration surface. Done means the ChatGPT, Prompt, System, and other titles can use custom highlight groups independently and the behavior is verified with a matching theme.

Written by the indexing model from the issue text.