set background-color for due date

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

frontend/src/routes/project/KanbanCard.svelte

@@ -32,7 +32,7 @@
     </span>
     {/if}
     {#if task.due_date}
-    <span class="due_date">
+    <span class="due_date" style={style}>
         {#if task.start_date}
         {task.start_date}
         {/if}

web/src/main/resources/web/css/default-color.css

@@ -91,13 +91,18 @@ textarea{
 }
 
 .kanban .state_10 .box,
+.kanban .state_10 .due_date,
 .kanban .state_20 .box,
+.kanban .state_20 .due_date,
 .kanban .state_40 .box,
-.kanban .state_100 .box{
+.kanban .state_40 .due_date,
+.kanban .state_100 .box
+.kanban .state_100 .due_date{
     background-color: orange;
 }
 
-.kanban .state_60 .box{
+.kanban .state_60 .box,
+.kanban .state_60 .due_date{
     background-color: #d3ff00;
 }