Edit in JSFiddle

table{
    /*style for table level*/
    thead{
        /*style for thead*/
        tr{
            
             /*style for tr*/
            th{
                 /*style for th*/
            }
        }
    } 
    
    tbody{
         /*style for tbody*/
        
        tr{
            &.even{
                 /*style for tr.even*/
            }
            &.odd{
                 /*style for tr.odd*/
            }
        }
    }
    
    
}