fix: query both stdin and stdout for background color on non-Windows …

…platforms

query.go

@@ -5,17 +5,12 @@ import (
 	"fmt"
 	"image/color"
 	"os"
+	"runtime"
 
 	"github.com/charmbracelet/x/term"
 )
 
-// BackgroundColor queries the terminal's background color. Typically, you'll
-// want to query against stdin and either stdout or stderr, depending on what
-// you're writing to.
-//
-// This function is intended for standalone Lip Gloss use only. If you're using
-// Bubble Tea, listen for tea.BackgroundColorMsg in your update function.
-func BackgroundColor(in *os.File, out *os.File) (color.Color, error) {
+func backgroundColor(in *os.File, out *os.File) (color.Color, error) {
 	state, err := term.MakeRaw(in.Fd())
 	if err != nil {
 		return nil, fmt.Errorf("error setting raw state to detect background color: %w", err)
@@ -31,6 +26,26 @@ func BackgroundColor(in *os.File, out *os.File) (color.Color, error) {
 	return bg, nil
 }
 
+// BackgroundColor queries the terminal's background color. Typically, you'll
+// want to query against stdin and either stdout or stderr, depending on what
+// you're writing to.
+//
+// This function is intended for standalone Lip Gloss use only. If you're using
+// Bubble Tea, listen for tea.BackgroundColorMsg in your update function.
+func BackgroundColor(in *os.File, out *os.File) (bg color.Color, err error) {
+	if runtime.GOOS == "windows" {
+		return backgroundColor(in, out)
+	} else {
+		// NOTE: On Unix, one of the given files must be a tty.
+		for _, f := range []*os.File{in, out} {
+			if bg, err = backgroundColor(f, f); err == nil {
+				return bg, nil
+			}
+		}
+	}
+	return
+}
+
 // HasDarkBackground detects whether the terminal has a light or dark
 // background.
 //