from tkinter import *
root = Tk()
root.geometry("400x400")
root.resizable(0, 0)
root.config(bg="#136b68")
root.title("Calcular o Troco")

titulo = Label(text="Calcular o Troco",
               font=("Arial", "28", "bold"),bg="#136b68",fg="#5de8e3")
titulo.place(relx=0.15, rely=0.05)
texto_sub1  = Label(text="Total a Pagar:",
                    font=("Arial", "15", "bold"),bg="#136b68",fg="#5de8e3")
texto_sub1.place(relx=0.15, rely=0.3)
texto_sub2  = Label(text="Total Pago:",
                    font=("Arial", "15", "bold"),bg="#136b68",fg="#5de8e3")
texto_sub2.place(relx=0.2, rely=0.45)


Total_Pagar = DoubleVar()
Total_Pagar_entrada = Entry(textvariable=Total_Pagar,
                             font=("Arial", "12", "bold"),
                             bg="white", fg="blue", justify='center')
Total_Pagar_entrada.place(relx=0.55, rely=0.3, relwidth=0.25)

Total_Pago = DoubleVar()
Total_Pago_entrada = Entry(textvariable=Total_Pago,
                             font=("Arial", "12", "bold"),
                             bg="white", fg="blue", justify='center')
Total_Pago_entrada.place(relx=0.55, rely=0.45, relwidth=0.25)
def app():
   pago= Total_Pago.get()
   a_pagar=Total_Pagar.get()
   diferença = a_pagar - pago
   if diferença < 0:
       troco = 0
   else:
       troco = diferença
   mensagem = f"O seu troco: € {troco} "
   resultado.set(mensagem)

def limpar():
    Total_Pago_entrada.delete(0, END)
    Total_Pagar_entrada.delete(0, END)
    resultado.set("")
but1 = Button(text="Calcular", bd=2, bg='#107db2', fg='white',
              font=('verdana', 12, 'bold'), command=app)
but1.place(relx=0.05, rely=0.6, relwidth=0.25, relheight=0.1)
but_limpar = Button(text="Limpar", bd=2, bg='#107db2', fg='white',
                    font=('verdana', 12, 'bold'), command=limpar)
but_limpar.place(relx=0.35, rely=0.6, relwidth=0.25, relheight=0.1)

but_sair = Button(text="Sair", bd=2, bg='#107db2', fg='white',
                    font=('verdana', 12, 'bold'), command=root.destroy)
but_sair.place(relx=0.65, rely=0.6, relwidth=0.25, relheight=0.1)

resultado = StringVar()
resultado_texto = Label(textvariable=resultado,
                           font=("Arial", 12, "bold"), bg="#cfe2f3")
resultado_texto.place(relx=0.05, rely=0.75, relwidth=0.9,relheight=0.2)
root.mainloop()