style: refine layout and theming in ObjectivesBoard

- Changed Card component to use 'column' variant for better layout consistency.
- Adjusted padding in task columns to improve spacing and visual hierarchy.
- Minor tweaks to border styles for enhanced clarity and alignment with theming.

components/kanban/ObjectivesBoard.tsx

@@ -32,7 +32,7 @@ export function ObjectivesBoard({
   return (
     <div className="bg-[var(--card)]/30 border-b border-[var(--accent)]/30">
       <div className="container mx-auto px-6 py-4">
-        <Card className="bg-[var(--card)] border-[var(--accent)]/30 shadow-[var(--accent)]/10 shadow-lg">
+        <Card variant="column" className="border-[var(--accent)]/30 shadow-[var(--accent)]/10">
           <CardHeader className="pb-3">
             <div className="flex items-center justify-between">
               <button
@@ -99,7 +99,7 @@ export function ObjectivesBoard({
                 <div className="grid grid-cols-1 lg:grid-cols-2 gap-6">
                   {/* Colonne En cours / À faire */}
                   <div className="space-y-3">
-                    <div className="flex items-center gap-2 pb-2 border-b border-[var(--accent)]/20">
+                    <div className="flex items-center gap-2 pt-2 pb-2 border-b border-[var(--accent)]/20">
                       <div className="w-2 h-2 bg-[var(--primary)] rounded-full"></div>
                       <h3 className="text-sm font-mono font-medium text-[var(--primary)] uppercase tracking-wider">
                         En cours / À faire
@@ -134,7 +134,7 @@ export function ObjectivesBoard({
 
                   {/* Colonne Terminé */}
                   <div className="space-y-3">
-                    <div className="flex items-center gap-2 pb-2 border-b border-[var(--accent)]/20">
+                    <div className="flex items-center gap-2 pt-2 pb-2 border-b border-[var(--accent)]/20">
                       <div className="w-2 h-2 bg-green-400 rounded-full"></div>
                       <h3 className="text-sm font-mono font-medium text-green-300 uppercase tracking-wider">
                         Terminé