🎨 style: update styles and layout in base templates and CSS files

app.py

@@ -2,7 +2,7 @@
 # -*- coding: utf-8 -*-
 
 import os
-from datetime import datetime, timedelta
+from datetime import datetime, timedelta, timezone
 from flask import Flask, render_template, request, redirect, url_for, flash, jsonify, session, g
 from flask_login import LoginManager, UserMixin, login_user, logout_user, login_required, current_user
 from flask_sqlalchemy import SQLAlchemy
@@ -292,7 +292,7 @@ def login():
         if user and user.check_password(password):
             login_user(user)
             # Aktualisiere letzten Login-Zeitpunkt
-            user.last_login = datetime.utcnow()
+            user.last_login = datetime.now(timezone.utc)
             db.session.commit()
             
             next_page = request.args.get('next')
@@ -708,7 +708,7 @@ def update_public_node(node_id):
             node.color_code = data['color_code']
         
         # Als bearbeitet markieren
-        node.last_modified = datetime.utcnow()
+        node.last_modified = datetime.now(timezone.utc)
         node.last_modified_by = current_user.id
         
         db.session.commit()
@@ -1057,7 +1057,7 @@ def update_note(note_id):
     if color_code:
         note.color_code = color_code
     
-    note.last_modified = datetime.utcnow()
+    note.last_modified = datetime.now(timezone.utc)
     db.session.commit()
     
     return jsonify({
@@ -1276,7 +1276,7 @@ def update_thought(thought_id):
     if 'color_code' in data:
         thought.color_code = data['color_code']
     
-    thought.last_modified = datetime.utcnow()
+    thought.last_modified = datetime.now(timezone.utc)
     db.session.commit()
     
     return jsonify({