selenium css selector 定位

1、 定位 任务 

driver.find_element(By.CSS_SELECTOR, 'ul.el-menu :nth-child(2)').click()

2.

driver.find_elements(By.CSS_SELECTOR, 'ul.el-menu')[0].\
    find_elements(By.CSS_SELECTOR,'li.el-menu-item')[2].click()