Fix search bar having different sizes on search and landing pages

invenio_theme_tuw/templates/semantic-ui/invenio_theme_tuw/header.html

@@ -32,7 +32,7 @@
               {%- block navbar_search %}
               <div class="navbar-item navbar-search-bar" id="header-search-bar">
                 <form class="ui form" action="{{ config.THEME_SEARCH_ENDPOINT }}" role="search">
-                  <div class="ui action icon input">
+                  <div class="ui fluid action icon input">
                     <input type="text" name="q" class="form-control" placeholder="{{ _('Search') }}">
                     <button type="submit" id="searchbutton" class="ui icon search button">
                       <i class="search icon"></i>

invenio_theme_tuw/templates/semantic-ui/invenio_theme_tuw/header_login.html

@@ -47,4 +47,4 @@
     <a href=" {{ url_for_security('logout') }}" class="ui button"><i class="sign-out icon"></i> {{ _('Log out') }}</a>
     {%- endif %}
   {%- endif %}
-{%- endif %}
+{%- endif %}
\ No newline at end of file