Scenario:
Client wanted to hide the ribbon from everyone except admin.
Solution:
1) Open your SharePoint master page
2) Add the following style in head section
<style type="text/css"> #s4-ribbonrow { display : none; } </style>3) Now find the start of the "s4-ribbonrow" tag and add following block before this:
<Sharepoint:SPSecurityTrimmedControl ID="SPSecurityTrimmedControl2" runat="server" PermissionsString="AddAndCustomizePages"> <style type="text/css"> #s4-ribbonrow { display : block; } </script> </Sharepoint:SPSecurityTrimmedControl>4) Save the new master page and publish it.