Selenium c# Unable To Get Test To Fail When Looking For Text

I am validating the presents of text within an address field and the text is present but no matter what I put in the expected string the test passes

string AddressLine1 = YourDetails.AddressLine1.GetCssValue("The Big Test House");

Another input element I am trying to retrieve text from:

<input id="first_name_text_box" name="firstName" class="StyledInput-sc-1p20bfl iaFJkJ" value="Cal">