How to change style values with a specific value

How to change style values with a specific value

Start with a sample:

  1. <body>
  2. <div style="max-width: 900px; .....">....</div>
  3. <div style="max-width: 1020px; margin-left: auto; margin-right: auto; .....">
  4. ...
  5. </div>
  6. ....
  7. </body>
How can I change the value of max-width: 1020px to max-width: "95%" for all <div> elements?
div panes with other (or no) max-width values should remain untouched.
Furthermore only those div panes should be considered which are immediately below (=child) of <body> (=no deeper childs elements)

How can  I code this in jQuery?

Thank you
Peter