index.haml

!!!
%html
  %head
    %script{src: 'js/jquery-1.11.2.min.js'}
    %link{href: 'https://maxcdn.bootstrapcdn.com/bootstrap/3.3.1/css/bootstrap.min.css', rel: 'stylesheet'}
    %link{href: 'https://maxcdn.bootstrapcdn.com/bootstrap/3.3.1/css/bootstrap-theme.min.css', rel: 'stylesheet'}
    %script{src: 'https://maxcdn.bootstrapcdn.com/bootstrap/3.3.1/js/bootstrap.min.js'}
    %link{href: 'style/style.css', rel: 'stylesheet'}
  %body
    %ul.nav.nav-pills.category_menu
    .form-inline
      .form-group-vertical   
        %input.form-control{type: 'text', name: 'how_many_from' }
        %select.form-control{name: 'from'}
      .form-group-vertical
        %input.form-control{type: 'text', name: 'how_many_to' }
        %select.form-control{name: 'to'}
      %button.btn.btn-default.go
        GO
    %script{src: 'js/unit_converter.js'}
    %script{src: 'js/app.js'}