make CMS work with stricter rules of php8

app/modules/filesinfolders.php

                 //$str = sprintf("%s", $str);
                 $this->content[$domain][$key."30text"] = sprintf(
                     "<div class=\"item %s %s\"><a name=\"%s\"></a>%s</div>",
-                    $page,
+                    '',
                     $key,
                     $key,
                     $str
             }
             $includeTemplates = array_key_exists('includeTemplates', $this->config)
                               ? $this->config['includeTemplates']
-                              : $f3->get('includeTemplates') ? : FALSE
+                              : ($f3->get('includeTemplates') ? : FALSE)
                               ;
             if ($includeTemplates) {
                 foreach($this->structs[$domain_key]['tpl'] as $key=>$file) {
                     $str = self::linkify($str);
                     $this->content[$domain][$key."00tpl"] = sprintf(
                         "<div class=\"item %s %s\">%s</div>",
-                        $page,
+                        '',
                         $key,
                         $str
                     );
             }
             $bulkIncludePic = array_key_exists('bulkIncludePic',$this->config)
                             ? $this->config['bulkIncludePic']
-                            : $f3->get('bulkIncludePic') ? : FALSE
+                            : ($f3->get('bulkIncludePic') ? : FALSE)
                             ;
             if ($bulkIncludePic) {
                 
                 
             }
             $bulkIncludeAudio = array_key_exists('bulkIncludeAudio',$this->config)
-                            ? $this->config['bulkIncludeAudio']
-                            : $f3->get('bulkIncludeAudio') ? : FALSE
-                            ;
+                              ? $this->config['bulkIncludeAudio']
+                              : ($f3->get('bulkIncludeAudio') ? : FALSE)
+                              ;
             if ($bulkIncludeAudio) {
                 foreach ($this->structs[$domain_key]['audio'] as $key=>$file) {
                     $this->content[$domain][$key."20audio"] = sprintf(

app/views/colors.css

 body {
     background-color: {{ @backgroundColor }};
+    <check if="{{ isset(@backgroundImage) }}">
     background-image: url(/{{ @backgroundImage }});
+    </check>
 }
 
 <repeat group="{{ @customVars }}" key="{{ @ikey }}" value="{{ @ivalue }}">

app/views/header2.htm

     </false>    
   </check>
 
-  <check if="{{ @subTitle }}">
+  <check if="{{ isset(@subTitle) }}">
     <h2>{{ @subTitle }}</h2>
   </check>
 
-  <check if="{{ @headerInfo1 || @headerInfo2 }}">
+  <check if="{{ isset(@headerInfo1) || isset(@headerInfo2) }}">
     <div class="headerInfo">
-      <span class="headerInfo1">{{ @headerInfo1 }}</span>
-      <span class="headerInfo2">{{ @headerInfo2 }}</span>
+      <span class="headerInfo1">{{ isset(@headerInfo1) ? @headerInfo1 : ''}}</span>
+      <span class="headerInfo2">{{ isset(@headerInfo2) ? @headerInfo2 : ''}}</span>
     </div>
   </check>
 </header>
 
-<check if="{{ @banner }}">
+<check if="{{ isset(@banner) }}">
   <true>
     <div id="site-banner"><img src="/{{ @banner }}" alt="{{ @subTitle }}" /></div>
   </true>

app/views/navigation.htm

 <ul class="nav level{{ @level }}">
     <repeat group="{{ @menu }}" key="{{ @key }}" value="{{ @item }}">
         
-        <li class="{{ @item.class }}"><a href="{{ @item.href }}">{{ @item.name | raw }}</a>
-            <check if="{{ is_array(@item.submenu) }}">
+        <li class="{{ @item.class }}">
+            
+            <a href="{{ @item.href }}">{{ @item.name | raw }}</a>
+            
+            <check if="{{ array_key_exists('submenu', @item) && is_array(@item.submenu) }}">
                 <include href="navigation.htm" with="menu={{ @item.submenu }},level={{ @level + 1 }}" />
             </check>
         </li>
     </repeat>
 </ul>
 
-
-
-<check if="{{ false }}">
-<ul>
-  <repeat group="{{ @menu }}" key="{{ @key }}" value="{{ @item }}">
-    <check if="{{ is_array(@item) }}">
-      <true>
-        <li class="{{ in_array(@key,$url)?'active':'away' }}">
-          <a href="{{ @SITE_URL }}/{{ @key }}{{ (@LANG=='de' ? '' : '?lang='.@LANG )}}">{{ @item.index }}</a>
-          
-          <check if="{{ count(@item) > 1 }}">
-            <ul>
-              <repeat group="{{ @item }}" key="{{ @key2 }}" value="{{ @item2 }}">
-                <check if="{{ @key2 != 'index'}}">
-                  <li class="{{ (in_array(@key2,$url) && in_array(@key,$url))?'active':'away' }}">
-                    <a href="{{ @SITE_URL }}/{{ @key }}/{{ @key2 }}{{ (@LANG=='de' ? '' : '?lang='.@LANG )}}">{{ @item2 }}</a>
-                  </li>
-                </check>
-              </repeat>
-            </ul>
-          </check>
-          
-        </li>
-      </true>
-      <false>
-        <li class="{{ in_array(@key,$url)?'active':'away' }}">
-          <a href="{{ @SITE_URL }}/{{ @key }}{{ (@LANG=='de' ? '' : '?lang='.@LANG )}}">{{ @item }}</a>
-        </li>
-      </false>
-    </check>
-  </repeat>
-</ul>
-</check>

main.cfg.sample

 ;default site template:
 template=tpl/index.html
 theme=style.css
+themepath=./
 
 external_links_open_in_new_window=false