panel/app/views/sites/_header.haml

.hyphens{ lang: site.default_locale }
  %h1= site.title
  %p.lead= site.description
  %form.mb-3{ action: site_posts_path }
    - @filter_params.each do |param, value|
      - next if param == 'q'
      %input{ type: 'hidden', name: param, value: value }
    .form-group.flex-grow-0.m-0
      %label{for: 'q'}= t('posts.index.search')
      .input-group
        %input#q.form-control.border.border-magenta.border-right-0{ type: 'search', name: 'q', value: @filter_params[:q] }
        .input-group-append
          %span.input-group-text.background-white.magenta.border.border-magenta.border-top.border-left-0.border-right.border-bottom
            %i.fa.fa-fw.fa-search
      %input.sr-only{ type: 'submit' }