Background color on bordered object

[wI2L]

Hello,

I'm not sure how to describe the problem with words in an understandable way, so a screenshot will be worth every words:

I have a succession of "tiles", as in the screenshot above, with rounded borders, and I'd like to "fill in" the area within the borders of each tile with a uniform background color (some of them, "A", "E", "D", "R" in this example).

However, for some reason, there is some kind of padding, even tho I haven't specified any. I have tried a few options, but couldn't ultimately achieve what I want to do.

The style definition of a "tile" is the following:

var (
	tileStyle = lipgloss.NewStyle().
		Width(3).
		Bold(true).
		Align(lipgloss.Center).
		BorderStyle(lipgloss.RoundedBorder()).
		Foreground(lipgloss.Color("#000000")).
		Background(lipgloss.Color("#FBE7D1")).
		Border(lipgloss.RoundedBorder()).
		BorderForeground(lipgloss.Color("#C5AC86"))
)

Thanks in advance.

Note: BorderBackground(), while it sounded appealing at first, gives the following result:

[wI2L]

Well, after a bit of digging, I assume that's simply not possible since the borders are rendered with characters that have their own rune width/height.

Do you have any ideas to achieve this by other means ?