diff --git a/internal/theme/theme.go b/internal/theme/theme.go
index 436ed02..0ab1e14 100644
--- a/internal/theme/theme.go
+++ b/internal/theme/theme.go
@@ -1,38 +1,174 @@
+// SPDX-FileCopyrightText: 2025 Daniel Morris <daniel@honestempire.com>
+// SPDX-License-Identifier: MIT
+
 package theme
 
 import (
+	"fmt"
 	"image/color"
+	"strconv"
+	"strings"
 
 	"github.com/charmbracelet/lipgloss"
 )
 
-// Theme defines the color scheme for the application.
-type Theme struct {
-	// Primary highlight color (teal) - used for Fang CLI rendering
-	Highlight color.RGBA
+// Config represents the raw theme configuration values.
+type Config struct {
+	Text      string
+	Muted     string
+	Highlight string
+	Success   string
+	Worry     string
+}
 
-	// Lipgloss color values for TUI
-	HighlightLipgloss lipgloss.Color
-	ActiveText        lipgloss.Color
-	MutedText         lipgloss.Color
-	SuccessText       lipgloss.Color
+// Theme defines the theme for the TUI and CLI help docs.
+type Theme struct {
+	Text      PaletteColor
+	Muted     PaletteColor
+	Highlight PaletteColor
+	Success   PaletteColor
+	Worry     PaletteColor
 
 	// UI characters
 	CursorChar string // Character shown next to selected todo item
 }
 
-// Default returns the default teal theme.
+// PaletteColor keeps a hex colour string for LipGloss and an RGBA version for Fang.
+type PaletteColor struct {
+	raw  string
+	rgba color.RGBA
+}
+
+// LipGloss converts the color to a lipgloss.Color.
+func (c PaletteColor) LipGloss() lipgloss.Color {
+	return lipgloss.Color(c.raw)
+}
+
+// RGBA exposes an image/color compliant representation of the color.
+func (c PaletteColor) RGBA() color.RGBA {
+	return c.rgba
+}
+
+// Default returns the default theme.
 func Default() Theme {
-	teal := color.RGBA{R: 0x58, G: 0xC5, B: 0xC7, A: 0xFF}
+	return MustFromConfig(Config{
+		Text:      "#FFFFFF",
+		Muted:     "#696969",
+		Highlight: "#58C5C7",
+		Success:   "#99CC00",
+		Worry:     "#FF7676",
+	})
+}
+
+// MustFromConfig creates a Theme from a Config and panics if parsing fails.
+func MustFromConfig(cfg Config) Theme {
+	t, err := FromConfig(cfg)
+	if err != nil {
+		panic(fmt.Sprintf("invalid theme configuration: %v", err))
+	}
+	return t
+}
+
+// FromConfig converts a Config into a ready-to-use Theme.
+func FromConfig(cfg Config) (Theme, error) {
+	text, err := parsePaletteColor(cfg.Text)
+	if err != nil {
+		return Theme{}, fmt.Errorf("parse text colour: %w", err)
+	}
+
+	muted, err := parsePaletteColor(cfg.Muted)
+	if err != nil {
+		return Theme{}, fmt.Errorf("parse muted colour: %w", err)
+	}
+
+	highlight, err := parsePaletteColor(cfg.Highlight)
+	if err != nil {
+		return Theme{}, fmt.Errorf("parse highlight colour: %w", err)
+	}
+
+	success, err := parsePaletteColor(cfg.Success)
+	if err != nil {
+		return Theme{}, fmt.Errorf("parse success colour: %w", err)
+	}
+
+	worry, err := parsePaletteColor(cfg.Worry)
+	if err != nil {
+		return Theme{}, fmt.Errorf("parse worry colour: %w", err)
+	}
 
 	return Theme{
-		Highlight:         teal,
-		HighlightLipgloss: "#58C5C7",
-		ActiveText:        "15",
-		MutedText:         "240",
-		SuccessText:       "42",
-		CursorChar:        "❯",
+		Text:       text,
+		Muted:      muted,
+		Highlight:  highlight,
+		Success:    success,
+		Worry:      worry,
+		CursorChar: "❯",
+	}, nil
+}
+
+func parsePaletteColor(input string) (PaletteColor, error) {
+	trimmed := strings.TrimSpace(input)
+	if trimmed == "" {
+		return PaletteColor{}, fmt.Errorf("colour cannot be blank")
+	}
+
+	hexValue, err := normalizeHex(trimmed)
+	if err != nil {
+		return PaletteColor{}, err
+	}
+
+	rgba, err := hexToRGBA(hexValue)
+	if err != nil {
+		return PaletteColor{}, err
+	}
+
+	return PaletteColor{raw: hexValue, rgba: rgba}, nil
+}
+
+func normalizeHex(input string) (string, error) {
+	s := strings.TrimPrefix(input, "#")
+	s = strings.ToLower(s)
+
+	switch len(s) {
+	case 3:
+		s = fmt.Sprintf("%c%c%c%c%c%c", s[0], s[0], s[1], s[1], s[2], s[2])
+	case 6:
+		// Sound.
+	default:
+		return "", fmt.Errorf("hex colour must be 3 or 6 characters, got %d", len(s))
+	}
+
+	for _, r := range s {
+		if !((r >= '0' && r <= '9') || (r >= 'a' && r <= 'f')) {
+			return "", fmt.Errorf("invalid hex digit %q", r)
+		}
+	}
+
+	return "#" + strings.ToUpper(s), nil
+}
+
+func hexToRGBA(hex string) (color.RGBA, error) {
+	s := strings.TrimPrefix(hex, "#")
+	if len(s) != 6 {
+		return color.RGBA{}, fmt.Errorf("hex colour must be 6 characters, got %d", len(s))
+	}
+
+	r, err := strconv.ParseUint(s[0:2], 16, 8)
+	if err != nil {
+		return color.RGBA{}, fmt.Errorf("parse red component: %w", err)
+	}
+
+	g, err := strconv.ParseUint(s[2:4], 16, 8)
+	if err != nil {
+		return color.RGBA{}, fmt.Errorf("parse green component: %w", err)
+	}
+
+	b, err := strconv.ParseUint(s[4:6], 16, 8)
+	if err != nil {
+		return color.RGBA{}, fmt.Errorf("parse blue component: %w", err)
 	}
+
+	return color.RGBA{R: uint8(r), G: uint8(g), B: uint8(b), A: 0xFF}, nil
 }
 
 // ContainerStyle returns the style for the main container.
@@ -44,15 +180,15 @@ func (t *Theme) ContainerStyle() lipgloss.Style {
 func (t *Theme) TabStyle() lipgloss.Style {
 	return lipgloss.NewStyle().
 		Padding(0, 2).
-		Foreground(t.MutedText)
+		Foreground(t.Muted.LipGloss())
 }
 
 // ActiveTabStyle returns the style for the active tab.
 func (t *Theme) ActiveTabStyle() lipgloss.Style {
 	return lipgloss.NewStyle().
 		Padding(0, 2).
-		Foreground(t.ActiveText).
-		Background(t.HighlightLipgloss).
+		Foreground(t.Text.LipGloss()).
+		Background(t.Highlight.LipGloss()).
 		Bold(true)
 }
 
@@ -63,27 +199,32 @@ func (t *Theme) ItemStyle() lipgloss.Style {
 
 // HighlightedItemStyle returns the style for the currently selected todo item.
 func (t *Theme) HighlightedItemStyle() lipgloss.Style {
-	return lipgloss.NewStyle().Foreground(t.HighlightLipgloss)
+	return lipgloss.NewStyle().Foreground(t.Highlight.LipGloss())
 }
 
 // CompletedTitleStyle returns the style for completed todo titles.
 func (t *Theme) CompletedTitleStyle() lipgloss.Style {
 	return lipgloss.NewStyle().
-		Foreground(t.MutedText).
+		Foreground(t.Muted.LipGloss()).
 		Strikethrough(true)
 }
 
 // DescriptionStyle returns the style for todo descriptions.
 func (t *Theme) DescriptionStyle() lipgloss.Style {
-	return lipgloss.NewStyle().Foreground(t.MutedText)
+	return lipgloss.NewStyle().Foreground(t.Muted.LipGloss())
 }
 
 // HelpStyle returns the style for help text.
 func (t *Theme) HelpStyle() lipgloss.Style {
-	return lipgloss.NewStyle().Foreground(t.MutedText)
+	return lipgloss.NewStyle().Foreground(t.Muted.LipGloss())
 }
 
 // SuccessStyle returns the style for success indicators.
 func (t *Theme) SuccessStyle() lipgloss.Style {
-	return lipgloss.NewStyle().Foreground(t.SuccessText)
+	return lipgloss.NewStyle().Foreground(t.Success.LipGloss())
+}
+
+// WorryStyle returns the style for warning/error indicators.
+func (t *Theme) WorryStyle() lipgloss.Style {
+	return lipgloss.NewStyle().Foreground(t.Worry.LipGloss())
 }
diff --git a/internal/theme/theme_test.go b/internal/theme/theme_test.go
new file mode 100644
index 0000000..8bb9504
--- /dev/null
+++ b/internal/theme/theme_test.go
@@ -0,0 +1,74 @@
+package theme
+
+import (
+	"image/color"
+	"testing"
+)
+
+func TestParsePaletteColorHex(t *testing.T) {
+	c, err := parsePaletteColor("#abcdef")
+	if err != nil {
+		t.Fatalf("parsePaletteColor returned error: %v", err)
+	}
+
+	want := color.RGBA{R: 0xAB, G: 0xCD, B: 0xEF, A: 0xFF}
+	if c.RGBA() != want {
+		t.Fatalf("expected RGBA %v, got %v", want, c.RGBA())
+	}
+
+	if c.LipGloss() != "#ABCDEF" {
+		t.Fatalf("expected lipgloss colour #ABCDEF, got %s", c.LipGloss())
+	}
+}
+
+func TestFromConfigInvalid(t *testing.T) {
+	cfg := Config{
+		Text:      "bogus",
+		Muted:     "#333",
+		Highlight: "#58C5C7",
+		Success:   "#99CC00",
+		Worry:     "#ff7676",
+	}
+
+	if _, err := FromConfig(cfg); err == nil {
+		t.Fatal("expected FromConfig to error for invalid colour")
+	}
+}
+
+func TestDefaultTheme(t *testing.T) {
+	th := Default()
+
+	if th.Highlight.LipGloss() != "#58C5C7" {
+		t.Fatalf("expected default highlight #58C5C7, got %s", th.Highlight.LipGloss())
+	}
+
+	if th.Success.RGBA() == (color.RGBA{}) {
+		t.Fatal("expected success colour to be initialised")
+	}
+
+	if th.Worry.RGBA() == (color.RGBA{}) {
+		t.Fatal("expected worry colour to be initialised")
+	}
+}
+
+func TestParsePaletteColorShorthand(t *testing.T) {
+	c, err := parsePaletteColor("#abc")
+	if err != nil {
+		t.Fatalf("parsePaletteColor returned error: %v", err)
+	}
+
+	want := color.RGBA{R: 0xAA, G: 0xBB, B: 0xCC, A: 0xFF}
+	if c.RGBA() != want {
+		t.Fatalf("expected RGBA %v, got %v", want, c.RGBA())
+	}
+
+	if c.LipGloss() != "#AABBCC" {
+		t.Fatalf("expected lipgloss colour #AABBCC, got %s", c.LipGloss())
+	}
+}
+
+func TestParsePaletteColorRejectsANSI(t *testing.T) {
+	if _, err := parsePaletteColor("15"); err == nil {
+		t.Fatal("expected ANSI value to be rejected")
+	}
+}
diff --git a/internal/tui/tui.go b/internal/tui/tui.go
index 58c8846..f07f1e4 100644
--- a/internal/tui/tui.go
+++ b/internal/tui/tui.go
@@ -17,14 +17,14 @@ import (
 	"github.com/unfunco/t/internal/theme"
 )
 
-// Tab represents a tab in the UI.
+// Tab represents a tab in the UI, which corresponds to a todo list.
 type Tab int
 
 const (
 	TabToday Tab = iota
 	TabTomorrow
 	TabTodo
-	tabCount
+	TabCount
 )
 
 // String implements the fmt.Stringer interface and returns the title of a Tab.
@@ -150,7 +150,7 @@ type Model struct {
 	titleInput       textinput.Model
 	descriptionInput textarea.Model
 	formTargetList   Tab
-	editingIndex     int // Index of todo being edited
+	editingIndex     int
 }
 
 // New creates a new TUI model with the provided todo lists.
@@ -296,7 +296,6 @@ func (m *Model) View() string {
 
 	var b strings.Builder
 
-	// Only show tabs if there are any todos in any list
 	if m.hasAnyTodos() {
 		b.WriteString(m.renderTabs())
 		b.WriteString("\n\n")
@@ -313,7 +312,7 @@ func (m *Model) View() string {
 func (m *Model) renderTabs() string {
 	var tabs []string
 
-	for i := TabToday; i < tabCount; i++ {
+	for i := TabToday; i < TabCount; i++ {
 		var style lipgloss.Style
 		if i == m.activeTab {
 			style = m.theme.ActiveTabStyle()
@@ -356,7 +355,7 @@ func (m *Model) renderList() string {
 		var titleStyle lipgloss.Style
 		if i == m.cursor {
 			if todo.Completed {
-				titleStyle = m.theme.HighlightedItemStyle().Foreground(m.theme.MutedText).Strikethrough(true)
+				titleStyle = m.theme.HighlightedItemStyle().Foreground(m.theme.Muted.LipGloss()).Strikethrough(true)
 			} else {
 				titleStyle = m.theme.HighlightedItemStyle()
 			}
@@ -370,7 +369,7 @@ func (m *Model) renderList() string {
 
 		var descStyle lipgloss.Style
 		if i == m.cursor {
-			descStyle = m.theme.HighlightedItemStyle().Foreground(m.theme.MutedText)
+			descStyle = m.theme.HighlightedItemStyle().Foreground(m.theme.Muted.LipGloss())
 		} else {
 			descStyle = m.theme.DescriptionStyle()
 		}
@@ -451,12 +450,12 @@ func (m *Model) cursorDown() {
 
 // nextTab moves to the next tab.
 func (m *Model) nextTab() {
-	m.activeTab = (m.activeTab + 1) % tabCount
+	m.activeTab = (m.activeTab + 1) % TabCount
 }
 
 // previousTab moves to the previous tab.
 func (m *Model) previousTab() {
-	m.activeTab = (m.activeTab + tabCount - 1) % tabCount
+	m.activeTab = (m.activeTab + TabCount - 1) % TabCount
 }
 
 // toggleCurrent toggles the completion status of the current todo.
@@ -627,12 +626,12 @@ func (m *Model) updateFormFocus() tea.Cmd {
 
 // nextFormList cycles to the next list option.
 func (m *Model) nextFormList() {
-	m.formTargetList = (m.formTargetList + 1) % tabCount
+	m.formTargetList = (m.formTargetList + 1) % TabCount
 }
 
 // previousFormList cycles to the previous list option.
 func (m *Model) previousFormList() {
-	m.formTargetList = (m.formTargetList + tabCount - 1) % tabCount
+	m.formTargetList = (m.formTargetList + TabCount - 1) % TabCount
 }
 
 // getListByTab returns the todo list for the given tab.
@@ -693,7 +692,7 @@ func (m *Model) renderForm() string {
 
 	b.WriteString(listLabel + "\n")
 
-	for i := TabToday; i < tabCount; i++ {
+	for i := TabToday; i < TabCount; i++ {
 		var listStyle lipgloss.Style
 		if i == m.formTargetList {
 			if m.formField == FormFieldList {
diff --git a/main.go b/main.go
index 2afff75..27ad496 100644
--- a/main.go
+++ b/main.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"image/color"
 	"os"
 
 	"github.com/charmbracelet/fang"
@@ -10,14 +11,6 @@ import (
 	"github.com/unfunco/t/internal/theme"
 )
 
-// customColorScheme returns a custom color scheme with teal headings.
-func customColorScheme(c lipgloss.LightDarkFunc) fang.ColorScheme {
-	scheme := fang.AnsiColorScheme(c)
-	// Override the title color to match the teal used in the TUI
-	scheme.Title = theme.Default().Highlight
-	return scheme
-}
-
 func main() {
 	if err := fang.Execute(
 		context.Background(),
@@ -28,3 +21,26 @@ func main() {
 		os.Exit(1)
 	}
 }
+
+func customColorScheme(c lipgloss.LightDarkFunc) fang.ColorScheme {
+	scheme := fang.AnsiColorScheme(c)
+	th := theme.Default()
+
+	scheme.Base = th.Text.RGBA()
+	scheme.Description = th.Muted.RGBA()
+	scheme.Comment = th.Muted.RGBA()
+	scheme.Flag = th.Highlight.RGBA()
+	scheme.FlagDefault = th.Muted.RGBA()
+	scheme.Command = th.Highlight.RGBA()
+	scheme.Program = th.Highlight.RGBA()
+	scheme.QuotedString = th.Success.RGBA()
+	scheme.Argument = th.Text.RGBA()
+	scheme.DimmedArgument = th.Muted.RGBA()
+	scheme.Help = th.Muted.RGBA()
+	scheme.Dash = th.Text.RGBA()
+	scheme.Title = th.Highlight.RGBA()
+	scheme.ErrorHeader = [2]color.Color{th.Text.RGBA(), th.Worry.RGBA()}
+	scheme.ErrorDetails = th.Worry.RGBA()
+
+	return scheme
+}