style: update Kanban components for improved background effects

- Adjusted background opacity in `Board` and `SwimlanesBase` components to enhance visual layering.
- Modified `Card` component to support a new `background` prop for better customization of column cards.
- Updated styles for `Card` variants to include new gradient effects and backdrop blur adjustments, improving overall aesthetics.

src/components/kanban/Board.tsx

@@ -81,7 +81,7 @@ export function KanbanBoard({ tasks, onCreateTask, onEditTask, onUpdateStatus, c
   };
 
   const content = (
-    <div className="h-full flex flex-col bg-[var(--background)]">
+    <div className="h-full flex flex-col bg-[var(--background)]/30">
       {/* Espacement supérieur */}
       <div className="pt-4"></div>
 

src/components/kanban/Column.tsx

@@ -30,7 +30,7 @@ export function KanbanColumn({ id, tasks, onCreateTask, onEditTask, compactView
   return (
     <div className="flex-shrink-0 w-72 md:w-72 lg:w-80 h-full">
       <DropZone ref={setNodeRef} isOver={isOver}>
-        <Card variant="column" className="h-full flex flex-col">
+        <Card background="column"variant="column" className="h-full flex flex-col">
           <CardHeader className="pb-4">
             <ColumnHeader
               title={statusConfig.label}

src/components/kanban/SwimlanesBase.tsx

@@ -185,7 +185,7 @@ export function SwimlanesBase({
   };
 
   const content = (
-    <div className="flex flex-col h-full bg-[var(--background)]">
+    <div className="flex flex-col h-full bg-[var(--background)]/30">
       {/* Espacement supérieur */}
       <div className="flex-shrink-0 py-2"></div>
 

src/components/ui/Card.tsx

@@ -12,7 +12,7 @@ const Card = forwardRef<HTMLDivElement, CardProps>(
   ({ className, variant = 'default', shadow = 'sm', border = 'default', background = 'default', ...props }, ref) => {
     const backgrounds = {
       default: 'bg-[var(--card)] bg-gradient-to-br from-[var(--card)] via-[color-mix(in_srgb,var(--card)_90%,var(--background)_10%)] to-[color-mix(in_srgb,var(--card)_75%,var(--background)_25%)] relative before:absolute before:inset-0 before:rounded-lg before:bg-gradient-to-br before:from-[color-mix(in_srgb,var(--primary)_8%,transparent)] before:via-[color-mix(in_srgb,var(--primary)_4%,transparent)] before:to-transparent before:opacity-80 before:pointer-events-none',
-      column: 'bg-[var(--card-column)] bg-gradient-to-br from-[var(--card-column)] via-[color-mix(in_srgb,var(--card-column)_90%,var(--background)_10%)] to-[color-mix(in_srgb,var(--card-column)_75%,var(--background)_25%)] relative before:absolute before:inset-0 before:rounded-lg before:bg-gradient-to-br before:from-[color-mix(in_srgb,var(--primary)_10%,transparent)] before:via-[color-mix(in_srgb,var(--primary)_5%,transparent)] before:to-transparent before:opacity-90 before:pointer-events-none',
+      column: 'bg-transparent bg-gradient-to-br from-transparent via-transparent to-transparent relative before:absolute before:inset-0 before:rounded-lg before:bg-gradient-to-br before:from-[color-mix(in_srgb,var(--primary)_10%,transparent)] before:via-[color-mix(in_srgb,var(--primary)_5%,transparent)] before:to-transparent before:opacity-90 before:pointer-events-none',
       muted: 'bg-[var(--muted)]/15 bg-gradient-to-br from-[var(--muted)]/15 via-[color-mix(in_srgb,var(--muted)_10%,var(--background)_5%)] to-[color-mix(in_srgb,var(--muted)_8%,var(--background)_7%)] relative before:absolute before:inset-0 before:rounded-lg before:bg-gradient-to-br before:from-transparent before:via-[color-mix(in_srgb,var(--muted)_12%,transparent)] before:to-transparent before:opacity-60 before:pointer-events-none'
     };
 
@@ -35,7 +35,7 @@ const Card = forwardRef<HTMLDivElement, CardProps>(
       default: 'shadow-lg shadow-[var(--card-shadow-medium)] relative before:absolute before:inset-0 before:rounded-lg before:bg-gradient-to-br before:from-[color-mix(in_srgb,var(--primary)_6%,transparent)] before:via-[color-mix(in_srgb,var(--primary)_3%,transparent)] before:to-transparent before:opacity-70 before:pointer-events-none',
       elevated: 'shadow-xl shadow-[var(--card-shadow-heavy)] relative before:absolute before:inset-0 before:rounded-lg before:bg-gradient-to-br before:from-[color-mix(in_srgb,var(--primary)_8%,transparent)] before:via-[color-mix(in_srgb,var(--primary)_4%,transparent)] before:to-[color-mix(in_srgb,var(--primary)_2%,transparent)] before:opacity-80 before:pointer-events-none',
       bordered: 'border-[var(--primary)]/40 shadow-xl shadow-[var(--primary)]/20 relative before:absolute before:inset-0 before:rounded-lg before:bg-gradient-to-br before:from-[color-mix(in_srgb,var(--primary)_10%,transparent)] before:via-[color-mix(in_srgb,var(--primary)_5%,transparent)] before:to-transparent before:opacity-90 before:pointer-events-none',
-      column: 'bg-[var(--card-column)] shadow-xl shadow-[var(--card-shadow-heavy)] relative before:absolute before:inset-0 before:rounded-lg before:bg-gradient-to-br before:from-[color-mix(in_srgb,var(--primary)_8%,transparent)] before:via-[color-mix(in_srgb,var(--primary)_4%,transparent)] before:to-[color-mix(in_srgb,var(--primary)_2%,transparent)] before:opacity-80 before:pointer-events-none',
+      column: 'bg-[var(--card-column)]/50 bg-gradient-to-br from-[var(--card-column)]/50 via-[color-mix(in_srgb,var(--card-column)_50%,var(--background)_50%)] to-[color-mix(in_srgb,var(--card-column)_40%,var(--background)_60%)] shadow-xl shadow-[var(--card-shadow-heavy)] relative before:absolute before:inset-0 before:rounded-lg before:bg-gradient-to-br before:from-[color-mix(in_srgb,var(--primary)_8%,transparent)] before:via-[color-mix(in_srgb,var(--primary)_4%,transparent)] before:to-[color-mix(in_srgb,var(--primary)_2%,transparent)] before:opacity-80 before:pointer-events-none',
       glass: 'bg-[var(--card)]/40 border border-[var(--border)]/60 backdrop-blur-md shadow-xl shadow-[var(--card-shadow-medium)] relative before:absolute before:inset-0 before:rounded-lg before:bg-gradient-to-br before:from-[color-mix(in_srgb,var(--primary)_12%,transparent)] before:via-[color-mix(in_srgb,var(--primary)_6%,transparent)] before:to-transparent before:opacity-90 before:pointer-events-none'
     };
 
@@ -48,7 +48,8 @@ const Card = forwardRef<HTMLDivElement, CardProps>(
       <div
         ref={ref}
         className={cn(
-          'rounded-lg backdrop-blur-sm transition-all duration-200',
+          'rounded-lg transition-all duration-200',
+          background === 'column' ? 'backdrop-blur-none' : 'backdrop-blur-sm',
           finalBackground,
           finalBorder,
           finalShadow,