Revise color configuration

7 files changed, 369 insertions, 289 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 89b1fa82..ee88c41f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -44,10 +44,10 @@ Non-matching items are displayed in a dimmed color by default, but you can
 change it with the `--color hidden:...` option.
 
 ```sh
+fzf --raw --color hidden:red
 fzf --raw --color hidden:red:strikethrough
-
-# To unset the default 'dim' attribute, prefix the color spec with 'regular'
-fzf --raw --color hidden:regular:red:strikethrough
+fzf --raw --color hidden:red:strikethrough:dim
+fzf --raw --color hidden:red:strikethrough:dim:italic
 ```
 
 #### Conditional actions for raw mode
@@ -104,7 +104,37 @@ fzf --gutter ' ' --color gutter:reverse
 
 As noted above, the `--gutter-raw CHAR` option was also added for customizing the gutter column in raw mode.
 
-### Compatibility changes
+### Breaking changes
+
+#### Hiding the gutter column
+
+In the previous versions, the recommended way to hide the gutter column was to
+set `--color gutter:-1`. That's because the gutter column was just a space
+character, reversed. But now that it's using a visible character (`▌`), applying
+the default color is no longer enough to hide it. Instead, you can set it to
+a space character.
+
+```sh
+# Hide the gutter column
+fzf --gutter ' '
+
+# Classic style
+fzf --gutter ' ' --color gutter:reverse
+```
+
+#### `--color` option
+
+In the previous versions, some elements had default style attributes applied and
+you would have to explicitly unset them with `regular` attribute if you wanted
+to reset them. This is no longer needed now, as the default style attributes
+are applied only when you do not specify any color or style for that element.
+
+```sh
+# No 'dim', just red and italic.
+fzf --ghost 'Type to search' --color ghost:red:italic
+```
+
+#### Compatibility changes
 
 Starting with this release, fzf is built with Go 1.23. Support for some old OS versions has been dropped.
 
diff --git a/src/options.go b/src/options.go
index d3be6821..79e016b6 100644
--- a/src/options.go
+++ b/src/options.go
@@ -572,6 +572,7 @@ type Options struct {
 	Multi             int
 	Ansi              bool
 	Mouse             bool
+	BaseTheme         *tui.ColorTheme
 	Theme             *tui.ColorTheme
 	Black             bool
 	Bold              bool
@@ -672,9 +673,9 @@ func defaultPreviewOpts(command string) previewOpts {
 func defaultOptions() *Options {
 	var theme *tui.ColorTheme
 	if os.Getenv("NO_COLOR") != "" {
-		theme = tui.NoColorTheme()
+		theme = tui.NoColorTheme
 	} else {
-		theme = tui.EmptyTheme()
+		theme = tui.EmptyTheme
 	}
 
 	return &Options{
@@ -1317,8 +1318,9 @@ func dupeTheme(theme *tui.ColorTheme) *tui.ColorTheme {
 	return &dupe
 }
 
-func parseTheme(defaultTheme *tui.ColorTheme, str string) (*tui.ColorTheme, error) {
+func parseTheme(defaultTheme *tui.ColorTheme, str string) (*tui.ColorTheme, *tui.ColorTheme, error) {
 	var err error
+	var baseTheme *tui.ColorTheme
 	theme := dupeTheme(defaultTheme)
 	rrggbb := regexp.MustCompile("^#[0-9a-fA-F]{6}$")
 	comma := regexp.MustCompile(`[\s,]+`)
@@ -1329,13 +1331,17 @@ func parseTheme(defaultTheme *tui.ColorTheme, str string) (*tui.ColorTheme, erro
 		}
 		switch str {
 		case "dark":
+			baseTheme = tui.Dark256
 			theme = dupeTheme(tui.Dark256)
 		case "light":
+			baseTheme = tui.Light256
 			theme = dupeTheme(tui.Light256)
 		case "base16", "16":
+			baseTheme = tui.Default16
 			theme = dupeTheme(tui.Default16)
 		case "bw", "no":
-			theme = tui.NoColorTheme()
+			baseTheme = tui.NoColorTheme
+			theme = dupeTheme(tui.NoColorTheme)
 		default:
 			fail := func() {
 				// Let the code proceed to simplify the error handling
@@ -1514,7 +1520,7 @@ func parseTheme(defaultTheme *tui.ColorTheme, str string) (*tui.ColorTheme, erro
 			}
 		}
 	}
-	return theme, err
+	return baseTheme, theme, err
 }
 
 func parseWalkerOpts(str string) (walkerOpts, error) {
@@ -2649,11 +2655,15 @@ func parseOptions(index *int, opts *Options, allArgs []string) error {
 		case "--color":
 			_, spec := optionalNextString()
 			if len(spec) == 0 {
-				opts.Theme = tui.EmptyTheme()
+				opts.Theme = tui.EmptyTheme
 			} else {
-				if opts.Theme, err = parseTheme(opts.Theme, spec); err != nil {
+				var baseTheme *tui.ColorTheme
+				if baseTheme, opts.Theme, err = parseTheme(opts.Theme, spec); err != nil {
 					return err
 				}
+				if baseTheme != nil {
+					opts.BaseTheme = baseTheme
+				}
 			}
 		case "--toggle-sort":
 			str, err := nextString("key name required")
@@ -2739,7 +2749,8 @@ func parseOptions(index *int, opts *Options, allArgs []string) error {
 		case "--no-mouse":
 			opts.Mouse = false
 		case "+c", "--no-color":
-			opts.Theme = tui.NoColorTheme()
+			opts.BaseTheme = tui.NoColorTheme
+			opts.Theme = tui.NoColorTheme
 		case "+2", "--no-256":
 			opts.Theme = tui.Default16
 		case "--black":
@@ -3616,23 +3627,6 @@ func postProcessOptions(opts *Options) error {
 		}
 	}
 
-	if opts.Bold {
-		theme := opts.Theme
-		boldify := func(c tui.ColorAttr) tui.ColorAttr {
-			dup := c
-			if (c.Attr & tui.AttrRegular) == 0 {
-				dup.Attr |= tui.BoldForce
-			}
-			return dup
-		}
-		theme.Current = boldify(theme.Current)
-		theme.CurrentMatch = boldify(theme.CurrentMatch)
-		theme.Prompt = boldify(theme.Prompt)
-		theme.Input = boldify(theme.Input)
-		theme.Cursor = boldify(theme.Cursor)
-		theme.Spinner = boldify(theme.Spinner)
-	}
-
 	// If --height option is not supported on the platform, just ignore it
 	if !tui.IsLightRendererSupported() && opts.Height.size > 0 {
 		opts.Height = heightSpec{}
diff --git a/src/options_test.go b/src/options_test.go
index 7b152d75..1494d960 100644
--- a/src/options_test.go
+++ b/src/options_test.go
@@ -300,8 +300,12 @@ func TestBind(t *testing.T) {
 }
 
 func TestColorSpec(t *testing.T) {
+	var base *tui.ColorTheme
 	theme := tui.Dark256
-	dark, _ := parseTheme(theme, "dark")
+	base, dark, _ := parseTheme(theme, "dark")
+	if *dark != *base {
+		t.Errorf("incorrect base theme returned")
+	}
 	if *dark != *theme {
 		t.Errorf("colors should be equivalent")
 	}
@@ -309,7 +313,10 @@ func TestColorSpec(t *testing.T) {
 		t.Errorf("point should not be equivalent")
 	}
 
-	light, _ := parseTheme(theme, "dark,light")
+	base, light, _ := parseTheme(theme, "dark,light")
+	if *light != *base {
+		t.Errorf("incorrect base theme returned")
+	}
 	if *light == *theme {
 		t.Errorf("should not be equivalent")
 	}
@@ -320,7 +327,7 @@ func TestColorSpec(t *testing.T) {
 		t.Errorf("point should not be equivalent")
 	}
 
-	customized, _ := parseTheme(theme, "fg:231,bg:232")
+	_, customized, _ := parseTheme(theme, "fg:231,bg:232")
 	if customized.Fg.Color != 231 || customized.Bg.Color != 232 {
 		t.Errorf("color not customized")
 	}
@@ -333,7 +340,7 @@ func TestColorSpec(t *testing.T) {
 		t.Errorf("colors should now be equivalent: %v, %v", tui.Dark256, customized)
 	}
 
-	customized, _ = parseTheme(theme, "fg:231,dark   bg:232")
+	_, customized, _ = parseTheme(theme, "fg:231,dark   bg:232")
 	if customized.Fg != tui.Dark256.Fg || customized.Bg == tui.Dark256.Bg {
 		t.Errorf("color not customized")
 	}
diff --git a/src/terminal.go b/src/terminal.go
index f3b9ccda..5d578540 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -1109,14 +1109,18 @@ func NewTerminal(opts *Options, eventBox *util.EventBox, executor *util.Executor
 		t.acceptNth = opts.AcceptNth(t.delimiter)
 	}
 
+	baseTheme := opts.BaseTheme
+	if baseTheme == nil {
+		baseTheme = renderer.DefaultTheme()
+	}
 	// This should be called before accessing tui.Color*
-	tui.InitTheme(opts.Theme, renderer.DefaultTheme(), opts.Black, opts.InputBorderShape.Visible(), opts.HeaderBorderShape.Visible())
+	tui.InitTheme(opts.Theme, baseTheme, opts.Bold, opts.Black, opts.InputBorderShape.Visible(), opts.HeaderBorderShape.Visible())
 
 	// Gutter character
 	var gutterChar, gutterRawChar string
 	if opts.Gutter != nil {
 		gutterChar = *opts.Gutter
-	} else if t.unicode && !t.theme.Gutter.Color.IsDefault() {
+	} else if t.unicode {
 		gutterChar = "▌"
 	} else {
 		gutterChar = " "
@@ -1125,7 +1129,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox, executor *util.Executor
 
 	if opts.GutterRaw != nil {
 		gutterRawChar = *opts.GutterRaw
-	} else if t.unicode && !t.theme.Gutter.Color.IsDefault() {
+	} else if t.unicode {
 		gutterRawChar = "▖"
 	} else {
 		gutterRawChar = ":"
diff --git a/src/tui/dummy.go b/src/tui/dummy.go
index a9888036..cb0ce0da 100644
--- a/src/tui/dummy.go
+++ b/src/tui/dummy.go
@@ -2,30 +2,7 @@
 
 package tui
 
-type Attr int32
-
-func HasFullscreenRenderer() bool {
-	return false
-}
-
-var DefaultBorderShape = BorderRounded
-
-func (a Attr) Merge(b Attr) Attr {
-	if b&AttrRegular > 0 {
-		// Only keep bold attribute set by the system
-		return (b &^ AttrRegular) | (a & BoldForce)
-	}
-
-	return (a &^ AttrRegular) | b
-}
-
 const (
-	AttrUndefined = Attr(0)
-	AttrRegular   = Attr(1 << 8)
-	AttrClear     = Attr(1 << 9)
-	BoldForce     = Attr(1 << 10)
-	FullBg        = Attr(1 << 11)
-
 	Bold          = Attr(1)
 	Dim           = Attr(1 << 1)
 	Italic        = Attr(1 << 2)
@@ -36,6 +13,12 @@ const (
 	StrikeThrough = Attr(1 << 7)
 )
 
+func HasFullscreenRenderer() bool {
+	return false
+}
+
+var DefaultBorderShape = BorderRounded
+
 func (r *FullscreenRenderer) Init() error                        { return nil }
 func (r *FullscreenRenderer) DefaultTheme() *ColorTheme          { return nil }
 func (r *FullscreenRenderer) Resize(maxHeightFunc func(int) int) {}
diff --git a/src/tui/tcell.go b/src/tui/tcell.go
index e4a6a988..f7c6884f 100644
--- a/src/tui/tcell.go
+++ b/src/tui/tcell.go
@@ -36,8 +36,6 @@ func (p ColorPair) style() tcell.Style {
 	return style.Foreground(asTcellColor(p.Fg())).Background(asTcellColor(p.Bg()))
 }
 
-type Attr int32
-
 type TcellWindow struct {
 	color         bool
 	windowType    WindowType
@@ -98,14 +96,6 @@ const (
 	Italic             = Attr(tcell.AttrItalic)
 )
 
-const (
-	AttrUndefined = Attr(0)
-	AttrRegular   = Attr(1 << 7)
-	AttrClear     = Attr(1 << 8)
-	BoldForce     = Attr(1 << 10)
-	FullBg        = Attr(1 << 11)
-)
-
 func (r *FullscreenRenderer) Bell() {
 	_screen.Beep()
 }
@@ -159,15 +149,6 @@ func (c Color) Style() tcell.Color {
 	}
 }
 
-func (a Attr) Merge(b Attr) Attr {
-	if b&AttrRegular > 0 {
-		// Only keep bold attribute set by the system
-		return (b &^ AttrRegular) | (a & BoldForce)
-	}
-
-	return (a &^ AttrRegular) | b
-}
-
 // handle the following as private members of FullscreenRenderer instance
 // they are declared here to prevent introducing tcell library in non-windows builds
 var (
diff --git a/src/tui/tui.go b/src/tui/tui.go
index ae9e8c49..563d3c2a 100644
--- a/src/tui/tui.go
+++ b/src/tui/tui.go
@@ -8,6 +8,25 @@ import (
 	"github.com/rivo/uniseg"
 )
 
+type Attr int32
+
+const (
+	AttrUndefined = Attr(0)
+	AttrRegular   = Attr(1 << 8)
+	AttrClear     = Attr(1 << 9)
+	BoldForce     = Attr(1 << 10)
+	FullBg        = Attr(1 << 11)
+)
+
+func (a Attr) Merge(b Attr) Attr {
+	if b&AttrRegular > 0 {
+		// Only keep bold attribute set by the system
+		return (b &^ AttrRegular) | (a & BoldForce)
+	}
+
+	return (a &^ AttrRegular) | b
+}
+
 // Types of user action
 //
 //go:generate stringer -type=EventType
@@ -275,6 +294,13 @@ func (a ColorAttr) IsColorDefined() bool {
 	return a.Color != colUndefined
 }
 
+func (a ColorAttr) IsAttrDefined() bool {
+	return a.Attr != AttrUndefined
+}
+func (a ColorAttr) IsUndefined() bool {
+	return !a.IsColorDefined() && !a.IsAttrDefined()
+}
+
 func NewColorAttr() ColorAttr {
 	return ColorAttr{Color: colUndefined, Attr: AttrUndefined}
 }
@@ -779,9 +805,11 @@ func NewFullscreenRenderer(theme *ColorTheme, forceBlack bool, mouse bool) Rende
 }
 
 var (
-	Default16 *ColorTheme
-	Dark256   *ColorTheme
-	Light256  *ColorTheme
+	NoColorTheme *ColorTheme
+	EmptyTheme   *ColorTheme
+	Default16    *ColorTheme
+	Dark256      *ColorTheme
+	Light256     *ColorTheme
 
 	ColPrompt               ColorPair
 	ColNormal               ColorPair
@@ -825,121 +853,120 @@ var (
 	ColInputLabel           ColorPair
 )
 
-func EmptyTheme() *ColorTheme {
-	return &ColorTheme{
-		Colored:          true,
-		Input:            ColorAttr{colUndefined, AttrUndefined},
-		Fg:               ColorAttr{colUndefined, AttrUndefined},
-		Bg:               ColorAttr{colUndefined, AttrUndefined},
-		ListFg:           ColorAttr{colUndefined, AttrUndefined},
-		ListBg:           ColorAttr{colUndefined, AttrUndefined},
-		AltBg:            ColorAttr{colUndefined, AttrUndefined},
-		SelectedFg:       ColorAttr{colUndefined, AttrUndefined},
-		SelectedBg:       ColorAttr{colUndefined, AttrUndefined},
-		SelectedMatch:    ColorAttr{colUndefined, AttrUndefined},
-		DarkBg:           ColorAttr{colUndefined, AttrUndefined},
-		Prompt:           ColorAttr{colUndefined, AttrUndefined},
-		Match:            ColorAttr{colUndefined, AttrUndefined},
-		Current:          ColorAttr{colUndefined, AttrUndefined},
-		CurrentMatch:     ColorAttr{colUndefined, AttrUndefined},
-		Spinner:          ColorAttr{colUndefined, AttrUndefined},
-		Info:             ColorAttr{colUndefined, AttrUndefined},
-		Cursor:           ColorAttr{colUndefined, AttrUndefined},
-		Marker:           ColorAttr{colUndefined, AttrUndefined},
-		Header:           ColorAttr{colUndefined, AttrUndefined},
-		Footer:           ColorAttr{colUndefined, AttrUndefined},
-		Border:           ColorAttr{colUndefined, AttrUndefined},
-		BorderLabel:      ColorAttr{colUndefined, AttrUndefined},
-		ListLabel:        ColorAttr{colUndefined, AttrUndefined},
-		ListBorder:       ColorAttr{colUndefined, AttrUndefined},
-		Ghost:            ColorAttr{colUndefined, Dim},
-		Disabled:         ColorAttr{colUndefined, AttrUndefined},
-		PreviewFg:        ColorAttr{colUndefined, AttrUndefined},
-		PreviewBg:        ColorAttr{colUndefined, AttrUndefined},
-		Gutter:           ColorAttr{colUndefined, AttrUndefined},
-		PreviewBorder:    ColorAttr{colUndefined, AttrUndefined},
-		PreviewScrollbar: ColorAttr{colUndefined, AttrUndefined},
-		PreviewLabel:     ColorAttr{colUndefined, AttrUndefined},
-		Separator:        ColorAttr{colUndefined, AttrUndefined},
-		Scrollbar:        ColorAttr{colUndefined, AttrUndefined},
-		InputBg:          ColorAttr{colUndefined, AttrUndefined},
-		InputBorder:      ColorAttr{colUndefined, AttrUndefined},
-		InputLabel:       ColorAttr{colUndefined, AttrUndefined},
-		HeaderBg:         ColorAttr{colUndefined, AttrUndefined},
-		HeaderBorder:     ColorAttr{colUndefined, AttrUndefined},
-		HeaderLabel:      ColorAttr{colUndefined, AttrUndefined},
-		FooterBg:         ColorAttr{colUndefined, AttrUndefined},
-		FooterBorder:     ColorAttr{colUndefined, AttrUndefined},
-		FooterLabel:      ColorAttr{colUndefined, AttrUndefined},
-		GapLine:          ColorAttr{colUndefined, AttrUndefined},
-		Nth:              ColorAttr{colUndefined, AttrUndefined},
-		Hidden:           ColorAttr{colUndefined, Dim},
-	}
-}
+func init() {
+	defaultColor := ColorAttr{colDefault, AttrUndefined}
+	undefined := ColorAttr{colUndefined, AttrUndefined}
 
-func NoColorTheme() *ColorTheme {
-	return &ColorTheme{
+	NoColorTheme = &ColorTheme{
 		Colored:          false,
-		Input:            ColorAttr{colDefault, AttrUndefined},
-		Fg:               ColorAttr{colDefault, AttrUndefined},
-		Bg:               ColorAttr{colDefault, AttrUndefined},
-		ListFg:           ColorAttr{colDefault, AttrUndefined},
-		ListBg:           ColorAttr{colDefault, AttrUndefined},
-		AltBg:            ColorAttr{colUndefined, AttrUndefined},
-		SelectedFg:       ColorAttr{colDefault, AttrUndefined},
-		SelectedBg:       ColorAttr{colDefault, AttrUndefined},
-		SelectedMatch:    ColorAttr{colDefault, AttrUndefined},
-		DarkBg:           ColorAttr{colDefault, AttrUndefined},
-		Prompt:           ColorAttr{colDefault, AttrUndefined},
-		Match:            ColorAttr{colDefault, Underline},
-		Current:          ColorAttr{colDefault, Reverse},
-		CurrentMatch:     ColorAttr{colDefault, Reverse | Underline},
-		Spinner:          ColorAttr{colDefault, AttrUndefined},
-		Info:             ColorAttr{colDefault, AttrUndefined},
-		Cursor:           ColorAttr{colDefault, AttrUndefined},
-		Marker:           ColorAttr{colDefault, AttrUndefined},
-		Header:           ColorAttr{colDefault, AttrUndefined},
-		Border:           ColorAttr{colDefault, AttrUndefined},
-		BorderLabel:      ColorAttr{colDefault, AttrUndefined},
-		Ghost:            ColorAttr{colDefault, Dim},
-		Disabled:         ColorAttr{colDefault, AttrUndefined},
-		PreviewFg:        ColorAttr{colDefault, AttrUndefined},
-		PreviewBg:        ColorAttr{colDefault, AttrUndefined},
-		Gutter:           ColorAttr{colDefault, AttrUndefined},
-		PreviewBorder:    ColorAttr{colDefault, AttrUndefined},
-		PreviewScrollbar: ColorAttr{colDefault, AttrUndefined},
-		PreviewLabel:     ColorAttr{colDefault, AttrUndefined},
-		ListLabel:        ColorAttr{colDefault, AttrUndefined},
-		ListBorder:       ColorAttr{colDefault, AttrUndefined},
-		Separator:        ColorAttr{colDefault, AttrUndefined},
-		Scrollbar:        ColorAttr{colDefault, AttrUndefined},
-		InputBg:          ColorAttr{colDefault, AttrUndefined},
-		InputBorder:      ColorAttr{colDefault, AttrUndefined},
-		InputLabel:       ColorAttr{colDefault, AttrUndefined},
-		HeaderBg:         ColorAttr{colDefault, AttrUndefined},
-		HeaderBorder:     ColorAttr{colDefault, AttrUndefined},
-		HeaderLabel:      ColorAttr{colDefault, AttrUndefined},
-		FooterBg:         ColorAttr{colDefault, AttrUndefined},
-		FooterBorder:     ColorAttr{colDefault, AttrUndefined},
-		FooterLabel:      ColorAttr{colDefault, AttrUndefined},
-		GapLine:          ColorAttr{colDefault, AttrUndefined},
-		Nth:              ColorAttr{colUndefined, AttrUndefined},
-		Hidden:           ColorAttr{colUndefined, Dim},
+		Input:            defaultColor,
+		Fg:               defaultColor,
+		Bg:               defaultColor,
+		ListFg:           defaultColor,
+		ListBg:           defaultColor,
+		AltBg:            undefined,
+		SelectedFg:       defaultColor,
+		SelectedBg:       defaultColor,
+		SelectedMatch:    defaultColor,
+		DarkBg:           defaultColor,
+		Prompt:           defaultColor,
+		Match:            defaultColor,
+		Current:          undefined,
+		CurrentMatch:     undefined,
+		Spinner:          defaultColor,
+		Info:             defaultColor,
+		Cursor:           defaultColor,
+		Marker:           defaultColor,
+		Header:           defaultColor,
+		Border:           undefined,
+		BorderLabel:      defaultColor,
+		Ghost:            undefined,
+		Disabled:         defaultColor,
+		PreviewFg:        defaultColor,
+		PreviewBg:        defaultColor,
+		Gutter:           undefined,
+		PreviewBorder:    defaultColor,
+		PreviewScrollbar: defaultColor,
+		PreviewLabel:     defaultColor,
+		ListLabel:        defaultColor,
+		ListBorder:       defaultColor,
+		Separator:        defaultColor,
+		Scrollbar:        defaultColor,
+		InputBg:          defaultColor,
+		InputBorder:      defaultColor,
+		InputLabel:       defaultColor,
+		HeaderBg:         defaultColor,
+		HeaderBorder:     defaultColor,
+		HeaderLabel:      defaultColor,
+		FooterBg:         defaultColor,
+		FooterBorder:     defaultColor,
+		FooterLabel:      defaultColor,
+		GapLine:          defaultColor,
+		Nth:              undefined,
+		Hidden:           undefined,
+	}
+
+	EmptyTheme = &ColorTheme{
+		Colored:          true,
+		Input:            undefined,
+		Fg:               undefined,
+		Bg:               undefined,
+		ListFg:           undefined,
+		ListBg:           undefined,
+		AltBg:            undefined,
+		SelectedFg:       undefined,
+		SelectedBg:       undefined,
+		SelectedMatch:    undefined,
+		DarkBg:           undefined,
+		Prompt:           undefined,
+		Match:            undefined,
+		Current:          undefined,
+		CurrentMatch:     undefined,
+		Spinner:          undefined,
+		Info:             undefined,
+		Cursor:           undefined,
+		Marker:           undefined,
+		Header:           undefined,
+		Footer:           undefined,
+		Border:           undefined,
+		BorderLabel:      undefined,
+		ListLabel:        undefined,
+		ListBorder:       undefined,
+		Ghost:            undefined,
+		Disabled:         undefined,
+		PreviewFg:        undefined,
+		PreviewBg:        undefined,
+		Gutter:           undefined,
+		PreviewBorder:    undefined,
+		PreviewScrollbar: undefined,
+		PreviewLabel:     undefined,
+		Separator:        undefined,
+		Scrollbar:        undefined,
+		InputBg:          undefined,
+		InputBorder:      undefined,
+		InputLabel:       undefined,
+		HeaderBg:         undefined,
+		HeaderBorder:     undefined,
+		HeaderLabel:      undefined,
+		FooterBg:         undefined,
+		FooterBorder:     undefined,
+		FooterLabel:      undefined,
+		GapLine:          undefined,
+		Nth:              undefined,
+		Hidden:           undefined,
 	}
-}
 
-func init() {
 	Default16 = &ColorTheme{
 		Colored:          true,
-		Input:            ColorAttr{colDefault, AttrUndefined},
-		Fg:               ColorAttr{colDefault, AttrUndefined},
-		Bg:               ColorAttr{colDefault, AttrUndefined},
-		ListFg:           ColorAttr{colUndefined, AttrUndefined},
-		ListBg:           ColorAttr{colUndefined, AttrUndefined},
-		AltBg:            ColorAttr{colUndefined, AttrUndefined},
-		SelectedFg:       ColorAttr{colUndefined, AttrUndefined},
-		SelectedBg:       ColorAttr{colUndefined, AttrUndefined},
-		SelectedMatch:    ColorAttr{colUndefined, AttrUndefined},
+		Input:            defaultColor,
+		Fg:               defaultColor,
+		Bg:               defaultColor,
+		ListFg:           undefined,
+		ListBg:           undefined,
+		AltBg:            undefined,
+		SelectedFg:       undefined,
+		SelectedBg:       undefined,
+		SelectedMatch:    undefined,
 		DarkBg:           ColorAttr{colGrey, AttrUndefined},
 		Prompt:           ColorAttr{colBlue, AttrUndefined},
 		Match:            ColorAttr{colGreen, AttrUndefined},
@@ -951,44 +978,45 @@ func init() {
 		Marker:           ColorAttr{colMagenta, AttrUndefined},
 		Header:           ColorAttr{colCyan, AttrUndefined},
 		Footer:           ColorAttr{colCyan, AttrUndefined},
-		Border:           ColorAttr{colDefault, Dim},
-		BorderLabel:      ColorAttr{colDefault, AttrUndefined},
-		Ghost:            ColorAttr{colUndefined, Dim},
-		Disabled:         ColorAttr{colUndefined, AttrUndefined},
-		PreviewFg:        ColorAttr{colUndefined, AttrUndefined},
-		PreviewBg:        ColorAttr{colUndefined, AttrUndefined},
-		Gutter:           ColorAttr{colUndefined, AttrUndefined},
-		PreviewBorder:    ColorAttr{colUndefined, AttrUndefined},
-		PreviewScrollbar: ColorAttr{colUndefined, AttrUndefined},
-		PreviewLabel:     ColorAttr{colUndefined, AttrUndefined},
-		ListLabel:        ColorAttr{colUndefined, AttrUndefined},
-		ListBorder:       ColorAttr{colUndefined, AttrUndefined},
-		Separator:        ColorAttr{colUndefined, AttrUndefined},
-		Scrollbar:        ColorAttr{colUndefined, AttrUndefined},
-		InputBg:          ColorAttr{colUndefined, AttrUndefined},
-		InputBorder:      ColorAttr{colUndefined, AttrUndefined},
-		InputLabel:       ColorAttr{colUndefined, AttrUndefined},
-		HeaderBg:         ColorAttr{colUndefined, AttrUndefined},
-		HeaderBorder:     ColorAttr{colUndefined, AttrUndefined},
-		HeaderLabel:      ColorAttr{colUndefined, AttrUndefined},
-		FooterBg:         ColorAttr{colUndefined, AttrUndefined},
-		FooterBorder:     ColorAttr{colUndefined, AttrUndefined},
-		FooterLabel:      ColorAttr{colUndefined, AttrUndefined},
-		GapLine:          ColorAttr{colUndefined, AttrUndefined},
-		Nth:              ColorAttr{colUndefined, AttrUndefined},
-		Hidden:           ColorAttr{colUndefined, Dim},
+		Border:           undefined,
+		BorderLabel:      defaultColor,
+		Ghost:            undefined,
+		Disabled:         undefined,
+		PreviewFg:        undefined,
+		PreviewBg:        undefined,
+		Gutter:           undefined,
+		PreviewBorder:    undefined,
+		PreviewScrollbar: undefined,
+		PreviewLabel:     undefined,
+		ListLabel:        undefined,
+		ListBorder:       undefined,
+		Separator:        undefined,
+		Scrollbar:        undefined,
+		InputBg:          undefined,
+		InputBorder:      undefined,
+		InputLabel:       undefined,
+		HeaderBg:         undefined,
+		HeaderBorder:     undefined,
+		HeaderLabel:      undefined,
+		FooterBg:         undefined,
+		FooterBorder:     undefined,
+		FooterLabel:      undefined,
+		GapLine:          undefined,
+		Nth:              undefined,
+		Hidden:           undefined,
 	}
+
 	Dark256 = &ColorTheme{
 		Colored:          true,
-		Input:            ColorAttr{colDefault, AttrUndefined},
-		Fg:               ColorAttr{colDefault, AttrUndefined},
-		Bg:               ColorAttr{colDefault, AttrUndefined},
-		ListFg:           ColorAttr{colUndefined, AttrUndefined},
-		ListBg:           ColorAttr{colUndefined, AttrUndefined},
-		AltBg:            ColorAttr{colUndefined, AttrUndefined},
-		SelectedFg:       ColorAttr{colUndefined, AttrUndefined},
-		SelectedBg:       ColorAttr{colUndefined, AttrUndefined},
-		SelectedMatch:    ColorAttr{colUndefined, AttrUndefined},
+		Input:            defaultColor,
+		Fg:               defaultColor,
+		Bg:               defaultColor,
+		ListFg:           undefined,
+		ListBg:           undefined,
+		AltBg:            undefined,
+		SelectedFg:       undefined,
+		SelectedBg:       undefined,
+		SelectedMatch:    undefined,
 		DarkBg:           ColorAttr{236, AttrUndefined},
 		Prompt:           ColorAttr{110, AttrUndefined},
 		Match:            ColorAttr{108, AttrUndefined},
@@ -1002,42 +1030,43 @@ func init() {
 		Footer:           ColorAttr{109, AttrUndefined},
 		Border:           ColorAttr{59, AttrUndefined},
 		BorderLabel:      ColorAttr{145, AttrUndefined},
-		Ghost:            ColorAttr{colUndefined, Dim},
-		Disabled:         ColorAttr{colUndefined, AttrUndefined},
-		PreviewFg:        ColorAttr{colUndefined, AttrUndefined},
-		PreviewBg:        ColorAttr{colUndefined, AttrUndefined},
-		Gutter:           ColorAttr{colUndefined, AttrUndefined},
-		PreviewBorder:    ColorAttr{colUndefined, AttrUndefined},
-		PreviewScrollbar: ColorAttr{colUndefined, AttrUndefined},
-		PreviewLabel:     ColorAttr{colUndefined, AttrUndefined},
-		ListLabel:        ColorAttr{colUndefined, AttrUndefined},
-		ListBorder:       ColorAttr{colUndefined, AttrUndefined},
-		Separator:        ColorAttr{colUndefined, AttrUndefined},
-		Scrollbar:        ColorAttr{colUndefined, AttrUndefined},
-		InputBg:          ColorAttr{colUndefined, AttrUndefined},
-		InputBorder:      ColorAttr{colUndefined, AttrUndefined},
-		InputLabel:       ColorAttr{colUndefined, AttrUndefined},
-		HeaderBg:         ColorAttr{colUndefined, AttrUndefined},
-		HeaderBorder:     ColorAttr{colUndefined, AttrUndefined},
-		HeaderLabel:      ColorAttr{colUndefined, AttrUndefined},
-		FooterBg:         ColorAttr{colUndefined, AttrUndefined},
-		FooterBorder:     ColorAttr{colUndefined, AttrUndefined},
-		FooterLabel:      ColorAttr{colUndefined, AttrUndefined},
-		GapLine:          ColorAttr{colUndefined, AttrUndefined},
-		Nth:              ColorAttr{colUndefined, AttrUndefined},
-		Hidden:           ColorAttr{colUndefined, Dim},
+		Ghost:            undefined,
+		Disabled:         undefined,
+		PreviewFg:        undefined,
+		PreviewBg:        undefined,
+		Gutter:           undefined,
+		PreviewBorder:    undefined,
+		PreviewScrollbar: undefined,
+		PreviewLabel:     undefined,
+		ListLabel:        undefined,
+		ListBorder:       undefined,
+		Separator:        undefined,
+		Scrollbar:        undefined,
+		InputBg:          undefined,
+		InputBorder:      undefined,
+		InputLabel:       undefined,
+		HeaderBg:         undefined,
+		HeaderBorder:     undefined,
+		HeaderLabel:      undefined,
+		FooterBg:         undefined,
+		FooterBorder:     undefined,
+		FooterLabel:      undefined,
+		GapLine:          undefined,
+		Nth:              undefined,
+		Hidden:           undefined,
 	}
+
 	Light256 = &ColorTheme{
 		Colored:          true,
-		Input:            ColorAttr{colDefault, AttrUndefined},
-		Fg:               ColorAttr{colDefault, AttrUndefined},
-		Bg:               ColorAttr{colDefault, AttrUndefined},
-		ListFg:           ColorAttr{colUndefined, AttrUndefined},
-		ListBg:           ColorAttr{colUndefined, AttrUndefined},
-		AltBg:            ColorAttr{colUndefined, AttrUndefined},
-		SelectedFg:       ColorAttr{colUndefined, AttrUndefined},
-		SelectedBg:       ColorAttr{colUndefined, AttrUndefined},
-		SelectedMatch:    ColorAttr{colUndefined, AttrUndefined},
+		Input:            defaultColor,
+		Fg:               defaultColor,
+		Bg:               defaultColor,
+		ListFg:           undefined,
+		ListBg:           undefined,
+		AltBg:            undefined,
+		SelectedFg:       undefined,
+		SelectedBg:       undefined,
+		SelectedMatch:    undefined,
 		DarkBg:           ColorAttr{251, AttrUndefined},
 		Prompt:           ColorAttr{25, AttrUndefined},
 		Match:            ColorAttr{66, AttrUndefined},
@@ -1051,34 +1080,34 @@ func init() {
 		Footer:           ColorAttr{31, AttrUndefined},
 		Border:           ColorAttr{145, AttrUndefined},
 		BorderLabel:      ColorAttr{59, AttrUndefined},
-		Ghost:            ColorAttr{colUndefined, Dim},
-		Disabled:         ColorAttr{colUndefined, AttrUndefined},
-		PreviewFg:        ColorAttr{colUndefined, AttrUndefined},
-		PreviewBg:        ColorAttr{colUndefined, AttrUndefined},
-		Gutter:           ColorAttr{colUndefined, AttrUndefined},
-		PreviewBorder:    ColorAttr{colUndefined, AttrUndefined},
-		PreviewScrollbar: ColorAttr{colUndefined, AttrUndefined},
-		PreviewLabel:     ColorAttr{colUndefined, AttrUndefined},
-		ListLabel:        ColorAttr{colUndefined, AttrUndefined},
-		ListBorder:       ColorAttr{colUndefined, AttrUndefined},
-		Separator:        ColorAttr{colUndefined, AttrUndefined},
-		Scrollbar:        ColorAttr{colUndefined, AttrUndefined},
-		InputBg:          ColorAttr{colUndefined, AttrUndefined},
-		InputBorder:      ColorAttr{colUndefined, AttrUndefined},
-		InputLabel:       ColorAttr{colUndefined, AttrUndefined},
-		HeaderBg:         ColorAttr{colUndefined, AttrUndefined},
-		HeaderBorder:     ColorAttr{colUndefined, AttrUndefined},
-		HeaderLabel:      ColorAttr{colUndefined, AttrUndefined},
-		FooterBg:         ColorAttr{colUndefined, AttrUndefined},
-		FooterBorder:     ColorAttr{colUndefined, AttrUndefined},
-		FooterLabel:      ColorAttr{colUndefined, AttrUndefined},
-		GapLine:          ColorAttr{colUndefined, AttrUndefined},
-		Nth:              ColorAttr{colUndefined, AttrUndefined},
-		Hidden:           ColorAttr{colUndefined, Dim},
+		Ghost:            undefined,
+		Disabled:         undefined,
+		PreviewFg:        undefined,
+		PreviewBg:        undefined,
+		Gutter:           undefined,
+		PreviewBorder:    undefined,
+		PreviewScrollbar: undefined,
+		PreviewLabel:     undefined,
+		ListLabel:        undefined,
+		ListBorder:       undefined,
+		Separator:        undefined,
+		Scrollbar:        undefined,
+		InputBg:          undefined,
+		InputBorder:      undefined,
+		InputLabel:       undefined,
+		HeaderBg:         undefined,
+		HeaderBorder:     undefined,
+		HeaderLabel:      undefined,
+		FooterBg:         undefined,
+		FooterBorder:     undefined,
+		FooterLabel:      undefined,
+		GapLine:          undefined,
+		Nth:              undefined,
+		Hidden:           undefined,
 	}
 }
 
-func InitTheme(theme *ColorTheme, baseTheme *ColorTheme, forceBlack bool, hasInputWindow bool, hasHeaderWindow bool) {
+func InitTheme(theme *ColorTheme, baseTheme *ColorTheme, boldify bool, forceBlack bool, hasInputWindow bool, hasHeaderWindow bool) {
 	if forceBlack {
 		theme.Bg = ColorAttr{colBlack, AttrUndefined}
 	}
@@ -1098,18 +1127,36 @@ func InitTheme(theme *ColorTheme, baseTheme *ColorTheme, forceBlack bool, hasInp
 	theme.Bg = o(baseTheme.Bg, theme.Bg)
 	theme.DarkBg = o(baseTheme.DarkBg, theme.DarkBg)
 	theme.Prompt = o(baseTheme.Prompt, theme.Prompt)
-	theme.Match = o(baseTheme.Match, theme.Match)
+	match := theme.Match
+	if !baseTheme.Colored && match.IsUndefined() {
+		match.Attr = Underline
+	}
+	theme.Match = o(baseTheme.Match, match)
 	// Inherit from 'fg', so that we don't have to write 'current-fg:dim'
 	// e.g. fzf --delimiter / --nth -1 --color fg:dim,nth:regular
-	theme.Current = theme.Fg.Merge(o(baseTheme.Current, theme.Current))
-	theme.CurrentMatch = o(baseTheme.CurrentMatch, theme.CurrentMatch)
+	current := theme.Current
+	if !baseTheme.Colored && current.IsUndefined() {
+		current.Attr = Reverse
+	}
+	theme.Current = theme.Fg.Merge(o(baseTheme.Current, current))
+	currentMatch := theme.CurrentMatch
+	if !baseTheme.Colored && currentMatch.IsUndefined() {
+		currentMatch.Attr = Reverse | Underline
+	}
+	theme.CurrentMatch = o(baseTheme.CurrentMatch, currentMatch)
 	theme.Spinner = o(baseTheme.Spinner, theme.Spinner)
 	theme.Info = o(baseTheme.Info, theme.Info)
 	theme.Cursor = o(baseTheme.Cursor, theme.Cursor)
 	theme.Marker = o(baseTheme.Marker, theme.Marker)
 	theme.Header = o(baseTheme.Header, theme.Header)
 	theme.Footer = o(baseTheme.Footer, theme.Footer)
-	theme.Border = o(baseTheme.Border, theme.Border)
+
+	// If border color is undefined, set it to default color with dim attribute.
+	border := theme.Border
+	if baseTheme.Border.IsUndefined() && border.IsUndefined() {
+		border.Attr = Dim
+	}
+	theme.Border = o(baseTheme.Border, border)
 	theme.BorderLabel = o(baseTheme.BorderLabel, theme.BorderLabel)
 
 	undefined := NewColorAttr()
@@ -1122,9 +1169,23 @@ func InitTheme(theme *ColorTheme, baseTheme *ColorTheme, forceBlack bool, hasInp
 	theme.SelectedFg = o(theme.ListFg, theme.SelectedFg)
 	theme.SelectedBg = o(theme.ListBg, theme.SelectedBg)
 	theme.SelectedMatch = o(theme.Match, theme.SelectedMatch)
-	theme.Ghost = o(theme.Input, theme.Ghost)
+
+	ghost := theme.Ghost
+	if ghost.IsUndefined() {
+		ghost.Attr = Dim
+	} else if ghost.IsColorDefined() && !ghost.IsAttrDefined() {
+		// Don't want to inherit 'bold' from 'input'
+		ghost.Attr = AttrRegular
+	}
+	theme.Ghost = o(theme.Input, ghost)
 	theme.Disabled = o(theme.Input, theme.Disabled)
-	theme.Gutter = o(theme.DarkBg, theme.Gutter)
+
+	// Use dim gutter on non-colored themes if undefined
+	gutter := theme.Gutter
+	if !baseTheme.Colored && gutter.IsUndefined() {
+		gutter.Attr = Dim
+	}
+	theme.Gutter = o(theme.DarkBg, gutter)
 	theme.PreviewFg = o(theme.Fg, theme.PreviewFg)
 	theme.PreviewBg = o(theme.Bg, theme.PreviewBg)
 	theme.PreviewLabel = o(theme.BorderLabel, theme.PreviewLabel)
@@ -1166,6 +1227,26 @@ func InitTheme(theme *ColorTheme, baseTheme *ColorTheme, forceBlack bool, hasInp
 	theme.FooterBorder = o(theme.Border, theme.FooterBorder)
 	theme.FooterLabel = o(theme.BorderLabel, theme.FooterLabel)
 
+	if boldify {
+		boldify := func(c ColorAttr) ColorAttr {
+			dup := c
+			if (c.Attr & AttrRegular) == 0 {
+				dup.Attr |= BoldForce
+			}
+			return dup
+		}
+		theme.Current = boldify(theme.Current)
+		theme.CurrentMatch = boldify(theme.CurrentMatch)
+		theme.Prompt = boldify(theme.Prompt)
+		theme.Input = boldify(theme.Input)
+		theme.Cursor = boldify(theme.Cursor)
+		theme.Spinner = boldify(theme.Spinner)
+	}
+
+	if theme.Hidden.IsUndefined() {
+		theme.Hidden.Attr = Dim
+	}
+
 	initPalette(theme)
 }