feat(tasks): add overdue filter; fix(ui): solid light-mode dropdown/navbar

- Backend:
  - Accept `overdue` query param in `tasks.list_tasks` and `tasks.my_tasks`
  - Filter tasks where `due_date < today` and status in ['todo','in_progress','review']
  - Use local date via `now_in_app_timezone().date()` to respect app timezone

- UI:
  - Add “Show overdue only” checkbox to `tasks/list.html` and `tasks/my_tasks.html`
  - Preserve checkbox state via template context

- Styles:
  - Enforce opaque white backgrounds for light-mode navbar and mobile navbar
  - Disable backdrop blur to prevent bleed-through
  - Normalize light-mode dropdown menu colors/borders for readability
  - Add light-theme fallback for `--bs-body-bg`
  - Tweak mobile navbar dropdown borders/shadows

Files:
- app/routes/tasks.py
- app/templates/tasks/list.html
- app/templates/tasks/my_tasks.html
- app/static/base.css
- app/static/mobile.css

Testing:
- Tasks and My Tasks: check “Show overdue only” → only overdue, non-completed/non-cancelled tasks appear
- Light mode: navbar and dropdowns show solid white backgrounds with clear borders/hover states
- Mobile: collapsed navbar menu is full-width, opaque, readable

app/routes/tasks.py

@@ -5,6 +5,7 @@ from app.models import Task, Project, User, TimeEntry
 from datetime import datetime, date
 from decimal import Decimal
 from app.utils.db import safe_commit
+from app.utils.timezone import now_in_app_timezone
 
 tasks_bp = Blueprint('tasks', __name__)
 
@@ -18,6 +19,8 @@ def list_tasks():
     project_id = request.args.get('project_id', type=int)
     assigned_to = request.args.get('assigned_to', type=int)
     search = request.args.get('search', '').strip()
+    overdue_param = request.args.get('overdue', '').strip().lower()
+    overdue = overdue_param in ['1', 'true', 'on', 'yes']
     
     query = Task.query
     
@@ -43,6 +46,14 @@ def list_tasks():
             )
         )
     
+    # Overdue filter (uses application's local date)
+    if overdue:
+        today_local = now_in_app_timezone().date()
+        query = query.filter(
+            Task.due_date < today_local,
+            Task.status.in_(['todo', 'in_progress', 'review'])
+        )
+    
     # Show user's tasks first, then others
     if not current_user.is_admin:
         query = query.filter(
@@ -72,7 +83,8 @@ def list_tasks():
         priority=priority,
         project_id=project_id,
         assigned_to=assigned_to,
-        search=search
+        search=search,
+        overdue=overdue
     )
 
 @tasks_bp.route('/tasks/create', methods=['GET', 'POST'])
@@ -339,6 +351,8 @@ def my_tasks():
     project_id = request.args.get('project_id', type=int)
     search = request.args.get('search', '').strip()
     task_type = request.args.get('task_type', '')  # '', 'assigned', 'created'
+    overdue_param = request.args.get('overdue', '').strip().lower()
+    overdue = overdue_param in ['1', 'true', 'on', 'yes']
 
     query = Task.query
 
@@ -374,6 +388,14 @@ def my_tasks():
             )
         )
 
+    # Overdue filter (uses application's local date)
+    if overdue:
+        today_local = now_in_app_timezone().date()
+        query = query.filter(
+            Task.due_date < today_local,
+            Task.status.in_(['todo', 'in_progress', 'review'])
+        )
+
     tasks = query.order_by(
         Task.priority.desc(),
         Task.due_date.asc(),
@@ -392,7 +414,8 @@ def my_tasks():
         priority=priority,
         project_id=project_id,
         search=search,
-        task_type=task_type
+        task_type=task_type,
+        overdue=overdue
     )
 
 @tasks_bp.route('/tasks/overdue')

app/static/base.css

@@ -23,6 +23,8 @@
     --card-spacing: 1.5rem;
     --mobile-section-spacing: 1.5rem;
     --mobile-card-spacing: 1rem;
+    /* Bootstrap interop (light theme fallback) */
+    --bs-body-bg: #ffffff;
 }
 
 /* Dark theme variables */
@@ -597,8 +599,10 @@ main {
 
 /* Enhanced Navigation Layout */
 .navbar {
-    background: white !important;
-    backdrop-filter: blur(10px);
+    background: #ffffff !important;
+    background-color: #ffffff !important; /* ensure solid fill */
+    -webkit-backdrop-filter: none !important;
+    backdrop-filter: none !important; /* avoid translucency */
     box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
     border-bottom: 1px solid var(--border-color);
     padding: 1rem 0;
@@ -611,6 +615,13 @@ main {
     background: #0b1220 !important;
     border-bottom-color: var(--border-color);
 }
+[data-theme="light"] .navbar,
+html[data-theme="light"] .navbar {
+    background: #ffffff !important;
+    background-color: #ffffff !important;
+    -webkit-backdrop-filter: none !important;
+    backdrop-filter: none !important;
+}
 [data-theme="dark"] .navbar-collapse {
     background: #0b1220 !important;
 }
@@ -921,6 +932,36 @@ h6 { font-size: 1rem; }
 [data-theme="dark"] .dropdown-item { color: var(--text-secondary) !important; }
 [data-theme="dark"] .dropdown-item:hover { background-color: #111827 !important; color: var(--text-primary) !important; }
 
+/* Light mode dropdown fixes (ensure solid background and proper contrast) */
+[data-theme="light"] .dropdown-menu,
+.navbar .dropdown-menu {
+    --bs-dropdown-bg: #ffffff;
+    --bs-dropdown-link-color: var(--text-primary);
+    --bs-dropdown-link-hover-bg: var(--light-color);
+    --bs-dropdown-link-hover-color: var(--text-primary);
+    --bs-dropdown-border-color: var(--border-color);
+    background-color: #ffffff !important;
+    border: 1px solid var(--border-color);
+    box-shadow: var(--card-shadow-hover);
+}
+
+[data-theme="light"] .dropdown-item,
+.navbar .dropdown-item {
+    color: var(--text-primary) !important;
+}
+
+[data-theme="light"] .dropdown-item:hover,
+.navbar .dropdown-item:hover {
+    background-color: var(--light-color) !important;
+    color: var(--text-primary) !important;
+}
+
+[data-theme="light"] .dropdown-divider,
+.navbar .dropdown-divider {
+    background-color: var(--border-color) !important;
+    opacity: 1;
+}
+
 /* Ensure dropdowns inside cards stack above adjacent content */
 .card .dropdown,
 .mobile-card .dropdown {

app/static/mobile.css

@@ -234,7 +234,10 @@
     .navbar {
         min-height: var(--mobile-nav-height);
         padding: 0.75rem 0;
-        background: white !important;
+        background: #ffffff !important;
+        background-color: #ffffff !important;
+        -webkit-backdrop-filter: none !important;
+        backdrop-filter: none !important;
         box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
     }
     
@@ -257,7 +260,7 @@
     }
     
     .navbar-collapse {
-        background: var(--bs-body-bg);
+        background: var(--bs-body-bg, #ffffff);
         border-top: 1px solid var(--border-color);
         margin-top: 0.75rem;
         padding: 1rem 0;
@@ -302,7 +305,7 @@
         float: none;
         width: 100%;
         margin: 0;
-        border: 2px solid var(--primary-color) !important;
+        border: 1px solid var(--border-color) !important;
         box-shadow: 0 8px 25px rgba(0, 0, 0, 0.25) !important;
         background: var(--bs-dropdown-bg, #ffffff) !important;
         background-color: var(--bs-dropdown-bg, #ffffff) !important; /* ensure solid bg */
@@ -406,7 +409,7 @@
         display: block !important;
         transform: none !important;
         background: var(--bs-dropdown-bg, #ffffff) !important;
-        border: 2px solid var(--primary-color) !important;
+        border: 1px solid var(--border-color) !important;
         box-shadow: 0 8px 25px rgba(0, 0, 0, 0.25) !important;
     }
     
@@ -416,7 +419,7 @@
     .navbar .dropdown-menu[data-bs-popper="static"] {
         display: block !important;
         background: var(--bs-dropdown-bg, #ffffff) !important;
-        border: 2px solid var(--primary-color) !important;
+        border: 1px solid var(--border-color) !important;
         box-shadow: 0 8px 25px rgba(0, 0, 0, 0.25) !important;
         z-index: 9999 !important;
     }

app/templates/tasks/list.html

@@ -150,6 +150,14 @@
                         {% endfor %}
                     </select>
                 </div>
+                <div class="col-md-2 col-sm-6 d-flex align-items-end">
+                    <div class="form-check">
+                        <input class="form-check-input" type="checkbox" value="1" id="overdue" name="overdue" {% if overdue %}checked{% endif %}>
+                        <label class="form-check-label" for="overdue">
+                            Show overdue only
+                        </label>
+                    </div>
+                </div>
                 <div class="col-12">
                     <div class="d-flex gap-2">
                         <button type="submit" class="btn btn-primary">

app/templates/tasks/my_tasks.html

@@ -147,6 +147,14 @@
                         <option value="created" {% if task_type == 'created' %}selected{% endif %}>Created by Me</option>
                     </select>
                 </div>
+                <div class="col-md-2 col-sm-6 d-flex align-items-end">
+                    <div class="form-check">
+                        <input class="form-check-input" type="checkbox" value="1" id="overdue" name="overdue" {% if overdue %}checked{% endif %}>
+                        <label class="form-check-label" for="overdue">
+                            Show overdue only
+                        </label>
+                    </div>
+                </div>
                 <div class="col-12">
                     <div class="d-flex gap-2">
                         <button type="submit" class="btn btn-primary">