Fix: Horizontales Scrollen auf Mobilgeräten endgültig behoben

- TaskCard: motion.div in overflow-hidden Wrapper gepackt
- TaskCard: overscrollBehaviorX auf motion.div gesetzt
- TaskCard: Titel und Badge-Zeile mit max-w-full/overflow-hidden abgesichert
- TasksWithCalendar: Negative Margins (-mx-4/-mx-6) am Calendar entfernt
- TasksWithCalendar: overflow-x-hidden auf Scrollable Task List
- index.css: overscroll-behavior-x: none global auf html/body/#root
- index.css: max-width: 100% als globale Absicherung gegen Overflow

client/src/components/TaskCard.tsx

@@ -295,6 +295,7 @@ export default function TaskCard({ task, onStartTimer, onStopTimer, onEdit, onDe
     : null;
 
   return (
+    <div className="overflow-hidden">
     <motion.div
       drag="x"
       dragConstraints={{ left: -50, right: 150 }} // Limit swipe distance
@@ -303,6 +304,7 @@ export default function TaskCard({ task, onStartTimer, onStopTimer, onEdit, onDe
       animate={controls}
       whileDrag={{ scale: 1.02, cursor: 'grabbing' }}
       className="touch-pan-y" // Allow vertical scroll, horizontal swipe
+      style={{ overscrollBehaviorX: 'none' }}
     >
       <ContextMenu>
         <ContextMenuTrigger asChild>
@@ -349,12 +351,12 @@ export default function TaskCard({ task, onStartTimer, onStopTimer, onEdit, onDe
                 }}
               >
                 {/* Parent Task Link rendered in title now */}
-                <h3 className={`font-medium text-sm leading-tight truncate ${task.status === 'done' ? 'line-through' : ''}`} data-testid={`text-task-title-${task.id}`}>
+                <h3 className={`font-medium text-sm leading-tight truncate max-w-full overflow-hidden ${task.status === 'done' ? 'line-through' : ''}`} data-testid={`text-task-title-${task.id}`}>
                   {parentTask ? (
-                    <span className="flex items-center gap-1 min-w-0">
-                      <span className="text-muted-foreground font-normal truncate shrink">{parentTask.title}</span>
+                    <span className="flex items-center gap-1 min-w-0 max-w-full overflow-hidden">
+                      <span className="text-muted-foreground font-normal truncate shrink min-w-0">{parentTask.title}</span>
                       <span className="text-muted-foreground shrink-0">›</span>
-                      <span className="truncate shrink">{task.title}</span>
+                      <span className="truncate shrink min-w-0">{task.title}</span>
                     </span>
                   ) : (
                     task.title
@@ -366,7 +368,7 @@ export default function TaskCard({ task, onStartTimer, onStopTimer, onEdit, onDe
                   </p>
                 )}
 
-                <div className="flex items-center gap-2 mt-3 flex-wrap">
+                <div className="flex items-center gap-2 mt-3 flex-wrap max-w-full overflow-hidden">
                   <Badge
                     variant="secondary"
                     className={`text-xs ${getPriorityColor(task.priority)}`}
@@ -701,5 +703,6 @@ export default function TaskCard({ task, onStartTimer, onStopTimer, onEdit, onDe
         onOpenChange={setIsShareModalOpen}
       />
     </motion.div>
+    </div>
   );
 }

client/src/components/TasksWithCalendar.tsx

@@ -355,7 +355,7 @@ export default function TasksWithCalendar({ tasks, onTaskUpdate, onTaskEdit, onT
       </div>
 
       {/* Scrollable Task List */}
-      <div className="flex-1 overflow-y-auto min-h-0 space-y-3 px-1 pb-4">
+      <div className="flex-1 overflow-y-auto overflow-x-hidden min-h-0 space-y-3 px-1 pb-4">
         {unscheduledTasks.length === 0 ? (
           <div className="text-center py-8">
             <p className="text-muted-foreground" data-testid="text-no-tasks">
@@ -409,7 +409,7 @@ export default function TasksWithCalendar({ tasks, onTaskUpdate, onTaskEdit, onT
       </div>
 
       {/* Calendar Section - Fixed at bottom */}
-      <div className="flex-none -mx-4 md:-mx-6 bg-background/95 backdrop-blur z-30 border-t mt-auto shadow-up-lg">
+      <div className="flex-none bg-background/95 backdrop-blur z-30 border-t mt-auto shadow-up-lg overflow-hidden">
         <div className="p-3">
           {/* Calendar Header */}
           <div className="flex items-center justify-between mb-3">

client/src/index.css

@@ -6,6 +6,17 @@
 html, body, #root {
   overflow-x: hidden;
   max-width: 100vw;
+  overscroll-behavior-x: none;
+}
+
+/* Prevent any element from causing horizontal overflow */
+* {
+  max-width: 100%;
+}
+
+/* Exceptions for elements that legitimately need wider content */
+.overflow-x-auto, [style*="grid-template-columns"] {
+  max-width: none;
 }
 
 /* LIGHT MODE */