CSS - is it good practice to override an attribute before styling it on the same selector? -

I mean something to ask for a while, for example when the default hr Hours {border: none; Border-top: 1px # 000 dashed; }

or this:

  hour {boundary-top: 1px # 000 dashed; Border-left: none; Boundary-right: none; Border bottom: None;    
 
 
 Your first example:  
  hour { Border: None; Border-top: 1px # 000 dashed; }   
 equals:  
  hour {border-top: none; Boundary-right: none; Border bottom: None; Border-left: none; Border-top: 1px # 000 dashed; }   
 ()  
 Therefore, it can be argued that you are applying the same property twice, but there is no need to worry about it It does not matter. / P>