Kivy如何在TextInput周围创建边框

#:kivy 2.0.0

BoxLayout:
    orientation: 'vertical'
    padding: 10

    TextInput:
        id: my_textinput
        size_hint_y: None
        height: 40
        background_color: 1, 1, 1, 1  # 设置背景颜色为白色
        foreground_color: 0, 0, 0, 1  # 设置文本颜色为黑色
        border: (10, 10, 10, 10)  # 设置边框的宽度为10
        border_color: 0, 0, 1, 1  # 设置边框颜色为蓝色

from kivy.app import App
from kivy.lang import Builder

class MyTextInputApp(App):
    def build(self):
        # 加载样式文件
        Builder.load_file('style.kv')
        return Builder.load_string('''
BoxLayout:
    orientation: 'vertical'
    padding: 10

    TextInput:
        id: my_textinput
        size_hint_y: None
        height: 40
        background_color: 1, 1, 1, 1
        foreground_color: 0, 0, 0, 1
        border: (10, 10, 10, 10)
        border_color: 0, 0, 1, 1
''')

if __name__ == '__main__':
    MyTextInputApp().run()