hover

import { css, cx } from '@emotion/css'

const color = 'yellow'

render(
  <div
    className={css`
      padding: 32px;
      background-color: hotpink;
      font-size: 24px;
      border-radius: 4px;
      &:hover {
        color: ${color};
      }
    `}
  >
    Hover to change color.
  </div>
)

import tkinter as tk

def on_enter(e):
    myButton['background'] = 'green'

def on_leave(e):
    myButton['background'] = 'SystemButtonFace'

root = tk.Tk()
myButton = tk.Button(root,text="Click Me")
myButton.grid()


myButton.bind("<Enter>", on_enter)
myButton.bind("<Leave>", on_leave)

root.mainloop()