Updates css class in layout

 reference -> AamAadmiParty/india-standalone-drupal#105
Fixes sitcky header at center

 reference -> AamAadmiParty/india-standalone-drupal#105
Adds border-bottom to sticky header

 reference -> AamAadmiParty/india-standalone-drupal#105
Merge pull request #114 from AamAadmiParty/tkuldeep/fix_sticky_header_105

Tkuldeep/fix sticky header 105