Feature: Welten-Navigation — Bottom-Nav+Header entfernt, Zurück-FAB (rund, dunkel), SW by-v644

backend/static/css/components.css

@@ -7635,27 +7635,35 @@ svg.empty-state-icon {
 }
 #worlds-fab:active { transform: scale(0.92); box-shadow: 0 2px 10px rgba(196,132,58,0.3); }
 
-/* Back-Button */
+/* Header + Bottom-Nav: vollständig entfernt — Welten übernehmen Navigation */
+#app-header  { display: none !important; }
+#bottom-nav  { display: none !important; }
+
+/* Zurück-FAB (gleiche Position wie worlds-fab, anderer Stil) */
 #worlds-back {
   position: fixed;
-  top: 0; left: 0; right: 0;
-  height: calc(env(safe-area-inset-top, 0px) + 44px);
-  padding-top: env(safe-area-inset-top, 0px);
+  bottom: calc(var(--safe-bottom) + 20px);
+  right: 20px;
+  width: 54px;
+  height: 54px;
+  border-radius: 50%;
+  background: rgba(20, 24, 36, 0.88);
+  border: 1.5px solid rgba(255, 255, 255, 0.18);
+  color: white;
+  cursor: pointer;
+  z-index: 200;
   display: none;
   align-items: center;
-  gap: 8px;
-  padding-left: 16px;
-  background: var(--c-bg);
-  border-bottom: 1px solid var(--c-border);
-  z-index: 200;
-  cursor: pointer;
-  color: var(--c-primary);
-  font-weight: 600;
-  font-size: var(--text-sm);
+  justify-content: center;
+  box-shadow: 0 4px 18px rgba(0, 0, 0, 0.40);
+  backdrop-filter: blur(14px);
+  -webkit-backdrop-filter: blur(14px);
+  transition: transform 0.12s, box-shadow 0.12s;
 }
 #worlds-back.worlds-back-visible { display: flex; }
+#worlds-back:active { transform: scale(0.92); box-shadow: 0 2px 8px rgba(0,0,0,0.3); }
 
-/* Hide existing header + bottom-nav when worlds are active */
+/* worlds-hidden bleibt für eventuelle andere Verwendung */
 .worlds-hidden { display: none !important; }
 
 /* ── JETZT WORLD ─────────────────────────────────────────── */

backend/static/css/design-system.css

@@ -105,9 +105,9 @@
   --transition-slow:   320ms ease;
 
   /* Navigation */
-  --nav-bottom-height: 64px;
+  --nav-bottom-height: 78px; /* Welten-Zurück-FAB: 54px + 20px bottom + 4px Abstand */
   --nav-sidebar-width: 240px;
-  --header-height:     56px;
+  --header-height:     0px;  /* Header entfernt — Welten-Navigation übernimmt */
 
   /* Safe Areas (iPhone Notch/Home Indicator) */
   --safe-top:    env(safe-area-inset-top, 0px);

backend/static/css/layout.css

@@ -19,6 +19,7 @@
   min-height:     0; /* iOS-Flex-Bug: ohne das scrollt body statt #page-content */
   overflow-y:     auto;
   overflow-x:     hidden;
+  padding-top:    var(--safe-top);
   padding-bottom: calc(var(--nav-bottom-height) + var(--safe-bottom) + 16px);
   -webkit-overflow-scrolling: touch;
 }