def check_anagrams(first_str: str, second_str: str) -> bool:
    """
    Two strings are anagrams if they are made of the same letters
    arranged differently (ignoring the case).
    >>> check_anagrams('Silent', 'Listen')
    True
    >>> check_anagrams('This is a string', 'Is this a string')
    True
    >>> check_anagrams('This is    a      string', 'Is     this a string')
    True
    >>> check_anagrams('There', 'Their')
    False
    """
    return (
        "".join(sorted(first_str.lower())).strip()
        == "".join(sorted(second_str.lower())).strip()
    )