Lip Gloss Box with Label

main.go

package main

import (
	"fmt"
	"strings"

	"github.com/charmbracelet/lipgloss"
)

type BoxWithLabel struct {
	BoxStyle   lipgloss.Style
	LabelStyle lipgloss.Style
}

func NewDefaultBoxWithLabel() BoxWithLabel {
	return BoxWithLabel{
		BoxStyle: lipgloss.NewStyle().
			Border(lipgloss.RoundedBorder()).
			BorderForeground(lipgloss.Color("63")).
			Padding(1),

		// You could, of course, also set background and foreground colors here 
		// as well.
		LabelStyle: lipgloss.NewStyle().
			PaddingTop(0).
			PaddingBottom(0).
			PaddingLeft(1).
			PaddingRight(1),
	}
}

func (b BoxWithLabel) Render(label, content string, width int) string {
	var (
		// Query the box style for some of its border properties so we can
		// essentially take the top border apart and put it around the label.
		border          lipgloss.Border     = b.BoxStyle.GetBorderStyle()
		topBorderStyler func(string) string = lipgloss.NewStyle().Foreground(b.BoxStyle.GetBorderTopForeground()).Render
		topLeft         string              = topBorderStyler(border.TopLeft)
		topRight        string              = topBorderStyler(border.TopRight)

		renderedLabel string = b.LabelStyle.Render(label)
	)

	// Render top row with the label
	borderWidth := b.BoxStyle.GetHorizontalBorderSize()
	cellsShort := max(0, width+borderWidth-lipgloss.Width(topLeft+topRight+renderedLabel))
	gap := strings.Repeat(border.Top, cellsShort)
	top := topLeft + renderedLabel + topBorderStyler(gap) + topRight

	// Render the rest of the box
	bottom := b.BoxStyle.Copy().
		BorderTop(false).
		Width(width).
		Render(content)

	// Stack the pieces
	return top + "\n" + bottom
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func main() {
	const body = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam imperdiet ultrices felis, et condimentum odio fringilla et. Etiam porttitor volutpat diam non gravida. Donec et condimentum nulla. Sed consectetur viverra fermentum. Pellentesque eget metus ut felis faucibus consectetur nec ac mi."

	b := NewDefaultBoxWithLabel()
	fmt.Println(b.Render("Title", body, 40))
}

Output:

Thank you very much for this. One small update; I had to use topBorderStyler func(...string) instead of topBorderStyler func(string). I think it changed in lipgloss here

Another change is to preserve box style background within the Render method.

topBorderStyler = lipgloss.NewStyle().
				Foreground(b.BoxStyle.GetBorderTopForeground()).
				Background(b.BoxStyle.GetBorderTopBackground()).
				Render