diff --git a/main.go b/main.go
index c87f1bf..1a601d6 100644
--- a/main.go
+++ b/main.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"image/color"
 	"strconv"
 	"strings"
 
@@ -62,6 +63,11 @@ func main() {
 		}
 	}
 
+	clearHistory := func() {
+		calculations = nil
+		historyList.Refresh()
+	}
+
 	// Roll button
 	rollButton := newCustomButton2WithImportance("ROLL", widget.HighImportance, roll)
 
@@ -69,87 +75,129 @@ func main() {
 		roll()
 	}
 
-	buttons := []fyne.CanvasObject{
-		newCustomButton2("H", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "H")
-		}),
-		newCustomButton2("dX", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "d")
-		}),
-		newCustomButton2("d4", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "d4")
-		}),
-		newCustomButton2("d6", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "d6")
-		}),
-		newCustomButton2("d8", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "d8")
-		}),
-		newCustomButton2("L", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "L")
-		}),
-		newCustomButton2("d10", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "d10")
-		}),
-		newCustomButton2("d12", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "d12")
-		}),
-		newCustomButton2("d20", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "d20")
-		}),
-		newCustomButton2("d100", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "d100")
-		}),
-		createCalcButton("7", diceInputEntry),
-		createCalcButton("8", diceInputEntry),
-		createCalcButton("9", diceInputEntry),
-		newCustomButton2("*", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "*")
-		}),
-		newCustomButton2("BKSP", func() {
-			text := diceInputEntry.Text
-			if len(text) > 0 {
-				diceInputEntry.SetText(text[:len(text)-1])
-			}
-		}),
-		createCalcButton("4", diceInputEntry),
-		createCalcButton("5", diceInputEntry),
-		createCalcButton("6", diceInputEntry),
-		newCustomButton2("/", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "/")
-		}),
-		newCustomButton2("C", func() {
-			diceInputEntry.SetText("")
-		}),
-		createCalcButton("1", diceInputEntry),
-		createCalcButton("2", diceInputEntry),
-		createCalcButton("3", diceInputEntry),
-		newCustomButton2("+", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "+")
-		}),
-		newCustomButton2("📊", func() {
-			diceInput := strings.TrimSpace(diceInputEntry.Text)
-			if diceInput == "" {
-				return
-			}
-			ShowStatisticsWindow(diceInput)
-			roll()
-		}),
-		newCustomButton2(".", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + ".")
-		}),
-		createCalcButton("0", diceInputEntry),
-		newCustomButton2("^", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "^")
-		}),
-		newCustomButton2("-", func() {
-			diceInputEntry.SetText(diceInputEntry.Text + "-")
-		}),
-		rollButton,
+	graphButton := newCustomButton2WithColors("📊", color.NRGBA{R: 46, G: 160, B: 67, A: 255}, color.White, func() {
+		diceInput := strings.TrimSpace(diceInputEntry.Text)
+		if diceInput == "" {
+			return
+		}
+		ShowStatisticsWindow(diceInput)
+		roll()
+	})
+
+	lButton := newCustomButton2("L", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "L")
+	})
+	hButton := newCustomButton2("H", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "H")
+	})
+	dxButton := newCustomButton2("dX", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "d")
+	})
+	d4Button := newCustomButton2("d4", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "d4")
+	})
+	d6Button := newCustomButton2("d6", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "d6")
+	})
+	d8Button := newCustomButton2("d8", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "d8")
+	})
+	d10Button := newCustomButton2("d10", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "d10")
+	})
+	d12Button := newCustomButton2("d12", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "d12")
+	})
+	d20Button := newCustomButton2("d20", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "d20")
+	})
+	d100Button := newCustomButton2("d100", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "d100")
+	})
+	sevenButton := createCalcButton("7", diceInputEntry)
+	eightButton := createCalcButton("8", diceInputEntry)
+	nineButton := createCalcButton("9", diceInputEntry)
+	fourButton := createCalcButton("4", diceInputEntry)
+	fiveButton := createCalcButton("5", diceInputEntry)
+	sixButton := createCalcButton("6", diceInputEntry)
+	oneButton := createCalcButton("1", diceInputEntry)
+	twoButton := createCalcButton("2", diceInputEntry)
+	threeButton := createCalcButton("3", diceInputEntry)
+	zeroButton := createCalcButton("0", diceInputEntry)
+	multiplyButton := newCustomButton2("*", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "*")
+	})
+	backspaceButton := newCustomButton2("BKSP", func() {
+		text := diceInputEntry.Text
+		if len(text) > 0 {
+			diceInputEntry.SetText(text[:len(text)-1])
+		}
+	})
+	divideButton := newCustomButton2("/", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "/")
+	})
+	clearButton := newCustomButton2("C", func() {
+		diceInputEntry.SetText("")
+	})
+	addButton := newCustomButton2("+", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "+")
+	})
+	acButton := newCustomButton2WithColors("AC", color.NRGBA{R: 198, G: 40, B: 40, A: 255}, color.White, clearHistory)
+	decimalButton := newCustomButton2(".", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + ".")
+	})
+	powerButton := newCustomButton2("^", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "^")
+	})
+	subtractButton := newCustomButton2("-", func() {
+		diceInputEntry.SetText(diceInputEntry.Text + "-")
+	})
+
+	keypadButtons := []fyne.CanvasObject{
+		lButton, hButton, dxButton, d4Button, d6Button, graphButton,
+		d8Button, d10Button, d12Button, d20Button, d100Button,
+		sevenButton, eightButton, nineButton, multiplyButton, backspaceButton, rollButton,
+		fourButton, fiveButton, sixButton, divideButton, clearButton,
+		oneButton, twoButton, threeButton, addButton, acButton,
+		decimalButton, zeroButton, powerButton, subtractButton,
 	}
 
-	buttonsContainer := container.New(newAspectRatioLayout(3.0/2.0, 7, 5))
-	for _, button := range buttons {
+	buttonSpans := map[fyne.CanvasObject]gridSpan{
+		lButton:         {row: 0, col: 0, rowSpan: 1, colSpan: 1},
+		hButton:         {row: 0, col: 1, rowSpan: 1, colSpan: 1},
+		dxButton:        {row: 0, col: 2, rowSpan: 1, colSpan: 1},
+		d4Button:        {row: 0, col: 3, rowSpan: 1, colSpan: 1},
+		d6Button:        {row: 0, col: 4, rowSpan: 1, colSpan: 1},
+		graphButton:     {row: 0, col: 5, rowSpan: 2, colSpan: 1},
+		d8Button:        {row: 1, col: 0, rowSpan: 1, colSpan: 1},
+		d10Button:       {row: 1, col: 1, rowSpan: 1, colSpan: 1},
+		d12Button:       {row: 1, col: 2, rowSpan: 1, colSpan: 1},
+		d20Button:       {row: 1, col: 3, rowSpan: 1, colSpan: 1},
+		d100Button:      {row: 1, col: 4, rowSpan: 1, colSpan: 1},
+		sevenButton:     {row: 2, col: 0, rowSpan: 1, colSpan: 1},
+		eightButton:     {row: 2, col: 1, rowSpan: 1, colSpan: 1},
+		nineButton:      {row: 2, col: 2, rowSpan: 1, colSpan: 1},
+		multiplyButton:  {row: 2, col: 3, rowSpan: 1, colSpan: 1},
+		backspaceButton: {row: 2, col: 4, rowSpan: 1, colSpan: 1},
+		rollButton:      {row: 2, col: 5, rowSpan: 4, colSpan: 1},
+		fourButton:      {row: 3, col: 0, rowSpan: 1, colSpan: 1},
+		fiveButton:      {row: 3, col: 1, rowSpan: 1, colSpan: 1},
+		sixButton:       {row: 3, col: 2, rowSpan: 1, colSpan: 1},
+		divideButton:    {row: 3, col: 3, rowSpan: 1, colSpan: 1},
+		clearButton:     {row: 3, col: 4, rowSpan: 1, colSpan: 1},
+		oneButton:       {row: 4, col: 0, rowSpan: 1, colSpan: 1},
+		twoButton:       {row: 4, col: 1, rowSpan: 1, colSpan: 1},
+		threeButton:     {row: 4, col: 2, rowSpan: 1, colSpan: 1},
+		addButton:       {row: 4, col: 3, rowSpan: 1, colSpan: 1},
+		acButton:        {row: 4, col: 4, rowSpan: 2, colSpan: 1},
+		decimalButton:   {row: 5, col: 0, rowSpan: 1, colSpan: 1},
+		zeroButton:      {row: 5, col: 1, rowSpan: 1, colSpan: 1},
+		powerButton:     {row: 5, col: 2, rowSpan: 1, colSpan: 1},
+		subtractButton:  {row: 5, col: 3, rowSpan: 1, colSpan: 1},
+	}
+
+	buttonsContainer := container.New(newSpanGridLayout(6, 6, buttonSpans))
+	for _, button := range keypadButtons {
 		buttonsContainer.Add(button)
 	}
 
diff --git a/ui.go b/ui.go
index 1cefe5d..ddfc81f 100644
--- a/ui.go
+++ b/ui.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"image/color"
+	"unicode/utf8"
 
 	"fyne.io/fyne/v2"
 	"fyne.io/fyne/v2/canvas"
@@ -80,6 +81,9 @@ type customButton2 struct {
 	Text       string
 	OnTapped   func()
 	Importance widget.Importance
+	TextSize   float32
+	Background color.Color
+	Foreground color.Color
 }
 
 func (b *customButton2) CreateRenderer() fyne.WidgetRenderer {
@@ -122,9 +126,12 @@ type customButton2Renderer struct {
 func (r *customButton2Renderer) Layout(size fyne.Size) {
 	r.background.Resize(size)
 	r.text.Resize(size)
-	newTextSize := size.Height * 0.4
-	if size.Width < newTextSize {
-		newTextSize = size.Width * 0.4
+	newTextSize := r.button.TextSize
+	if newTextSize <= 0 {
+		newTextSize = size.Height * 0.4
+		if size.Width < newTextSize {
+			newTextSize = size.Width * 0.4
+		}
 	}
 	r.text.TextSize = newTextSize
 }
@@ -135,6 +142,7 @@ func (r *customButton2Renderer) MinSize() fyne.Size {
 
 func (r *customButton2Renderer) Refresh() {
 	r.text.Text = r.button.Text
+	r.text.TextSize = r.button.TextSize
 	r.text.Color = r.button.textColor()
 	r.text.Refresh()
 	r.background.FillColor = r.button.backgroundColor()
@@ -149,6 +157,9 @@ func (r *customButton2Renderer) Destroy() {
 }
 
 func (b *customButton2) backgroundColor() color.Color {
+	if b.Background != nil {
+		return b.Background
+	}
 	variant := fyne.CurrentApp().Settings().ThemeVariant()
 	switch b.Importance {
 	case widget.HighImportance:
@@ -159,6 +170,9 @@ func (b *customButton2) backgroundColor() color.Color {
 }
 
 func (b *customButton2) textColor() color.Color {
+	if b.Foreground != nil {
+		return b.Foreground
+	}
 	variant := fyne.CurrentApp().Settings().ThemeVariant()
 	switch b.Importance {
 	case widget.HighImportance:
@@ -187,6 +201,17 @@ func newCustomButton2WithImportance(label string, importance widget.Importance,
 	return b
 }
 
+func newCustomButton2WithColors(label string, background, foreground color.Color, onTap func()) *customButton2 {
+	b := &customButton2{
+		Text:       label,
+		OnTapped:   onTap,
+		Background: background,
+		Foreground: foreground,
+	}
+	b.ExtendBaseWidget(b)
+	return b
+}
+
 // customEntry is a custom entry widget with configurable text size
 type customEntry struct {
 	widget.Entry
@@ -302,3 +327,103 @@ func (a *aspectRatioLayout) Layout(objects []fyne.CanvasObject, size fyne.Size)
 func (a *aspectRatioLayout) MinSize(objects []fyne.CanvasObject) fyne.Size {
 	return fyne.NewSize(10, 10)
 }
+
+type gridSpan struct {
+	row     int
+	col     int
+	rowSpan int
+	colSpan int
+}
+
+type spanGridLayout struct {
+	rows  int
+	cols  int
+	spans map[fyne.CanvasObject]gridSpan
+}
+
+func newSpanGridLayout(rows, cols int, spans map[fyne.CanvasObject]gridSpan) fyne.Layout {
+	return &spanGridLayout{
+		rows:  rows,
+		cols:  cols,
+		spans: spans,
+	}
+}
+
+func (s *spanGridLayout) Layout(objects []fyne.CanvasObject, size fyne.Size) {
+	if s.rows <= 0 || s.cols <= 0 {
+		return
+	}
+
+	cellWidth := size.Width / float32(s.cols)
+	cellHeight := size.Height / float32(s.rows)
+	uniformTextSize := float32(0)
+
+	for _, o := range objects {
+		button, ok := o.(*customButton2)
+		if !ok {
+			continue
+		}
+
+		span, ok := s.spans[o]
+		if !ok {
+			continue
+		}
+
+		rowSpan := max(span.rowSpan, 1)
+		colSpan := max(span.colSpan, 1)
+		buttonSize := fyne.NewSize(float32(colSpan)*cellWidth, float32(rowSpan)*cellHeight)
+		candidateSize := maxUniformButtonTextSize(button.Text, buttonSize)
+		if candidateSize <= 0 {
+			continue
+		}
+		if uniformTextSize == 0 || candidateSize < uniformTextSize {
+			uniformTextSize = candidateSize
+		}
+	}
+
+	for _, o := range objects {
+		if button, ok := o.(*customButton2); ok {
+			button.TextSize = uniformTextSize
+		}
+
+		span, ok := s.spans[o]
+		if !ok {
+			continue
+		}
+
+		rowSpan := max(span.rowSpan, 1)
+		colSpan := max(span.colSpan, 1)
+
+		x := float32(span.col) * cellWidth
+		y := float32(span.row) * cellHeight
+		width := float32(colSpan) * cellWidth
+		height := float32(rowSpan) * cellHeight
+
+		o.Move(fyne.NewPos(x, y))
+		o.Resize(fyne.NewSize(width, height))
+	}
+}
+
+func (s *spanGridLayout) MinSize(objects []fyne.CanvasObject) fyne.Size {
+	return fyne.NewSize(10, 10)
+}
+
+func maxUniformButtonTextSize(label string, size fyne.Size) float32 {
+	const (
+		horizontalPaddingFactor = 0.75
+		heightFactor            = 0.42
+		avgCharWidthFactor      = 0.62
+	)
+
+	maxByHeight := size.Height * heightFactor
+	charCount := utf8.RuneCountInString(label)
+	if charCount <= 0 {
+		return maxByHeight
+	}
+
+	maxByWidth := (size.Width * horizontalPaddingFactor) / (float32(charCount) * avgCharWidthFactor)
+	if maxByWidth < maxByHeight {
+		return maxByWidth
+	}
+	return maxByHeight
+}