Describe the bug

Hi. I was adding support for Snacks in my colorscheme, but I couldn't get the highlight groups for the notifier.show_history() float window title and border:

Here I'm using this undocumented hl groups, but none of them affects the float window title and/or border:

local test_hl = { fg = "#ff00ff", bg = "#00ff00" }
local ret = {
  -- etc.
  SnacksNotifierHistory = test_hl, -- Float window Normal
  SnacksNotifierHistoryDateTime = test_hl, -- Dates in entries
  SnacksNotifierHistoryTitle = test_hl, -- Changes the `Snacks` text for each log entry 
}

Maybe related to this line:

Snacks.config.style("notification.history", {
  -- etc.
  wo = { winhighlight = "Normal:SnacksNotifierHistory" },
})

For example, if changed to something like:

wo = {
  winhighlight = "Normal:SnacksNotifierHistory,FloatBorder:SnacksNotifierHistoryBorder,FloatTitle:SnacksNotifierHistoryTitle",
},

Then I could change the border and title:

Expected behavior

On my first approach I was expecting that the float border/title follows SnacksNormal. I don't know if that could be the appropriate hl or not, but it would be great if this could be adjusted, specially for floating windows bg transparency and related settings.