margin-left
        +
           35px : border-left-width
        +
            0px : padding-left
        +
           50px : width
        +
            0px : padding-right
        +
           15px : border-right-width
        +
            0px : margin-right
        +
          400px : right (80% of 500px == 400px)
        ====================
          500px : width of containing block (width of Initial Containing Block)

   so used left offset value must be 0px .

  */
  </style>
 </head>

 <body>

  