如何向Fyne UI应用程序添加填充，字体大小和颜色

I have this sample app code below for a UI I'm implementing using the fyne toolkit, and cant figure out how to align the buttons to the left, makes top text bigger, and add colours.

I've tried trying to create a custom theme to implement the UI features I need, but my understanding of the godoc for the fyne toolkit is lacking. Is there a doc someone can point me to to make this work? or provide me with some pointers, as the toolkit is poorly documented

this is my sample app code

package main

import (
    "fyne.io/fyne"
    "fyne.io/fyne/app"
    "fyne.io/fyne/layout"
    "fyne.io/fyne/theme"
    "fyne.io/fyne/widget"
)

func main() {
    a := app.New()
    a.Settings().SetTheme(theme.LightTheme())
    w := a.NewWindow("myapp")
    w.Resize(fyne.NewSize(340, 600))
    w.SetContent(widget.NewVBox(
        widget.NewLabelWithStyle("myApp version1", fyne.TextAlignLeading, fyne.TextStyle{Bold: true}),
        widget.NewLabelWithStyle("Welcome to 
 myAPp", fyne.TextAlignLeading, fyne.TextStyle{Bold: true}),
        layout.NewSpacer(),
        widget.NewButton("Register", func() {
            a.Quit()
        }),
        widget.NewButton("Login", func() {
            a.Quit()
        }),
    ))
    w.ShowAndRun()
}