def wait_appear_by_css_selector(
        self,
        css_selector: str,
        wait_timeout: int = 30
    ) -> WebElementIn the active browser, wait for the element to appear by the given CSS selector.
Parameters:
 css_selector[Required]: str
   The CSS selector to find the element.
 wait_timeout: int
   Timeout for the operation, the unit is second, and the default value is 30 seconds.
Returns:
 WebElement object, or None if the element does not appear.
Example:
from clicknium import clicknium as cc
chrome_tab = cc.chrome.open("https://bing.com")
#  wait element appear by CSS selector
webelement = chrome_tab.wait_appear_by_css_selector("#sb_form_q")
if webelement:
    webelement.highlight()
