diff --git a/frontend/package-lock.json b/frontend/package-lock.json
index 0937479..4b2fe99 100644
--- a/frontend/package-lock.json
+++ b/frontend/package-lock.json
@@ -23,6 +23,7 @@
         "react-leaflet": "^5.0.0",
         "react-leaflet-markercluster": "^5.0.0-rc.0",
         "react-router-dom": "^7.3.0",
+        "react-toastify": "^11.0.5",
         "recharts": "^2.15.1",
         "tailwindcss": "^4.0.9"
       },
@@ -4459,6 +4460,19 @@
         "react-dom": "^16.8.0 || ^17.0.0 || ^18.0.0 || ^19.0.0"
       }
     },
+    "node_modules/react-toastify": {
+      "version": "11.0.5",
+      "resolved": "https://registry.npmjs.org/react-toastify/-/react-toastify-11.0.5.tgz",
+      "integrity": "sha512-EpqHBGvnSTtHYhCPLxML05NLY2ZX0JURbAdNYa6BUkk+amz4wbKBQvoKQAB0ardvSarUBuY4Q4s1sluAzZwkmA==",
+      "license": "MIT",
+      "dependencies": {
+        "clsx": "^2.1.1"
+      },
+      "peerDependencies": {
+        "react": "^18 || ^19",
+        "react-dom": "^18 || ^19"
+      }
+    },
     "node_modules/react-transition-group": {
       "version": "4.4.5",
       "resolved": "https://registry.npmjs.org/react-transition-group/-/react-transition-group-4.4.5.tgz",
diff --git a/frontend/package.json b/frontend/package.json
index cfcf2cb..c66a9c5 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -25,6 +25,7 @@
     "react-leaflet": "^5.0.0",
     "react-leaflet-markercluster": "^5.0.0-rc.0",
     "react-router-dom": "^7.3.0",
+    "react-toastify": "^11.0.5",
     "recharts": "^2.15.1",
     "tailwindcss": "^4.0.9"
   },
diff --git a/frontend/src/App.jsx b/frontend/src/App.jsx
index 0defcb6..c72565c 100644
--- a/frontend/src/App.jsx
+++ b/frontend/src/App.jsx
@@ -2,6 +2,9 @@ import React, { useState, useEffect, useMemo, useRef } from "react";
 import { BrowserRouter as Router, Route, Routes } from "react-router-dom";
 import Cookies from "js-cookie";
 
+import { ToastContainer } from 'react-toastify';
+import 'react-toastify/dist/ReactToastify.css';
+
 import Navbar from "./components/Navbar";
 import Statistics from "./components/Statistics.jsx";
 import Help  from "./components/Help.jsx";
@@ -441,62 +444,65 @@ function App() {
     }, [memoizedFilteredMarkers]);
 
     return (
-        <Router>
-            <Navbar />
-            <Routes>
-                <Route
-                    path="/"
-                    element={
-                        <div style={{ height: "100vh", width: "100vw", display: "flex", position: "relative", paddingTop: "5vh" }}>
-                            {loading && <LoadingOverlay message={"Loading data..."} />}
-                            <div
-                                style={{
-                                    position: "absolute",
-                                    top: "1vh",
-                                    height: "5vh",
-                                    width: "250px", minWidth: "50px",
-                                    left: "50%",
-                                    transform: "translateX(-50%)",
-                                    zIndex: 1000,
-                                    ...(window.innerWidth < 800 ? { top: "auto", bottom: "10vh" } : {})
-                                }}
-                            >
-                                <input
-                                    type="text"
-                                    onChange={(e) => handleSearchChange(e)}
-                                    placeholder="Search..."
+        <>
+            <Router>
+                <Navbar />
+                <Routes>
+                    <Route
+                        path="/"
+                        element={
+                            <div style={{ height: "100vh", width: "100vw", display: "flex", position: "relative", paddingTop: "5vh" }}>
+                                {loading && <LoadingOverlay message={"Loading data..."} />}
+                                <div
                                     style={{
-                                        width: "250px", fontSize: "16px",
-                                        top: "6vh", marginTop: "5vh",
-                                        padding: "10px", background: "rgba(255, 255, 255, 0.9)", color: "black",
-                                        borderRadius: "10px", overflow: "hidden"
+                                        position: "absolute",
+                                        top: "1vh",
+                                        height: "5vh",
+                                        width: "250px", minWidth: "50px",
+                                        left: "50%",
+                                        transform: "translateX(-50%)",
+                                        zIndex: 1000,
+                                        ...(window.innerWidth < 800 ? { top: "auto", bottom: "10vh" } : {})
                                     }}
-                                />
-                            </div>
-                            <Sidebar
-                                selectedSources={selectedSources}
-                                setSelectedSources={setSelectedSources}
-                                clusteringEnabled={clusteringEnabled}
-                                setClusteringEnabled={setClusteringEnabled}
-                                fetchData={fetchData}
-                                userLocationAvailable={userLocationAvailable}
-                                showFavouritesOnly={showFaovouritesOnly}
-                                setShowFavouritesOnly={setShowFavouritesOnly}
-                            />
-                            <div style={{ flex: 1 }}>
-                                <MapComponent
-                                    markers={filteredMarkers}
-                                    clusteringEnabled={clusteringEnabled}
-                                    userLocationAvailable={userLocationAvailable}
+                                >
+                                    <input
+                                        type="text"
+                                        onChange={(e) => handleSearchChange(e)}
+                                        placeholder="Search..."
+                                        style={{
+                                            width: "250px", fontSize: "16px",
+                                            top: "6vh", marginTop: "5vh",
+                                            padding: "10px", background: "rgba(255, 255, 255, 0.9)", color: "black",
+                                            borderRadius: "10px", overflow: "hidden"
+                                        }}
                                     />
+                                </div>
+                                <Sidebar
+                                    selectedSources={selectedSources}
+                                    setSelectedSources={setSelectedSources}
+                                    clusteringEnabled={clusteringEnabled}
+                                    setClusteringEnabled={setClusteringEnabled}
+                                    fetchData={fetchData}
+                                    userLocationAvailable={userLocationAvailable}
+                                    showFavouritesOnly={showFaovouritesOnly}
+                                    setShowFavouritesOnly={setShowFavouritesOnly}
+                                />
+                                <div style={{ flex: 1 }}>
+                                    <MapComponent
+                                        markers={filteredMarkers}
+                                        clusteringEnabled={clusteringEnabled}
+                                        userLocationAvailable={userLocationAvailable}
+                                        />
+                                </div>
                             </div>
-                        </div>
-                    }
-                />
-                <Route path="/statistics" element={<Statistics />} />
-                <Route path="/help" element={<Help />} />
-            </Routes>
-        </Router>
+                        }
+                    />
+                    <Route path="/statistics" element={<Statistics />} />
+                    <Route path="/help" element={<Help />} />
+                </Routes>
+            </Router>
+            <ToastContainer position="bottom-right"/>
+        </>
     );
 }
 export default App;
\ No newline at end of file
diff --git a/frontend/src/components/Sidebar.jsx b/frontend/src/components/Sidebar.jsx
index f7eb267..e5beb72 100644
--- a/frontend/src/components/Sidebar.jsx
+++ b/frontend/src/components/Sidebar.jsx
@@ -1,6 +1,7 @@
 import React, { useState, useEffect, useRef } from "react";
 import PropTypes from 'prop-types';
 import Cookies from "js-cookie";
+import { toast } from 'react-toastify';
 
 const menuData = [
     {
@@ -19,7 +20,7 @@ const menuData = [
                     { id: "terminated", name: "Terminated", endsec: true },
                     { id: "early", name: "Early" },
                     { id: "on-time", name: "On-time" },
-                    { id: "late", name: "Late" },
+                    { id: "late", name: "Late", endsec: true  },
                 ],
             },
             { id: "irish-rail-stations", name: "Irish Rail Stations" },
@@ -42,11 +43,22 @@ const menuData = [
             { id: "enabled", name: "Enabled" },
             { id: "disabled", name: "Disabled", endsec: true },
             { id: "park-and-ride", name: "Must be Park & Ride" },
-            { id: "cycle-and-ride", name: "Must be Cycle & Ride" },
+            { id: "cycle-and-ride", name: "Must be Cycle & Ride", endsec: true  },
         ],
     },
 ];
 
+const sectionGroups = [
+    ["irish-rail", "bus", "luas-stops"],
+    ["irish-rail-trains", "irish-rail-stations"],
+    ["mainline", "suburban", "dart"],
+    ["running", "not-yet-running", "terminated"],
+    ["early", "on-time", "late"],
+    ["buses", "bus-stops"],
+    ["red-line", "green-line"],
+    ["enabled", "disabled"],
+];
+
 const customDefaultChecked = ["mainline","suburban","dart","running","not-yet-running","terminated","early","on-time","late","disabled","buses","irish-rail-trains","luas-stops","enabled","green-line","red-line","irish-rail","bus"]
 
 const getAllDefaultCheckedIds = (data) => {
@@ -66,14 +78,26 @@ const getAllDefaultCheckedIds = (data) => {
 };
 
 const CheckboxItem = ({ item, selectedSources, setSelectedSources, enabledSources, setEnabledSources, level = 0, parentChecked = true }) => {
-    console.log("item id: " + item.id);
-    console.log(selectedSources.includes(item.id));
-
     const isChecked = selectedSources.includes(item.id);
     const isDisabled = !parentChecked;  // Disable if any parent is not checked
     const isEnabled = isChecked && parentChecked;  // Only enabled if checked and parent is checked
 
     const handleCheckboxChange = () => {
+        if (isChecked) {
+            if (item.id != "park-and-ride" && item.id != "cycle-and-ride") {
+                // Find which section this item is in
+                const section = sectionGroups.find(group => group.includes(item.id));
+
+                if (section.length > 1) {
+                    const selectedInSection = section.filter(id => selectedSources.includes(id));
+                    if (selectedInSection.length === 1 && selectedInSection[0] === item.id) {
+                        toast.warn("At least one item in this section must be selected");
+                        return; // Don't allow unchecking the last one
+                    }
+                }
+            }
+        }
+
         setSelectedSources((prev) =>
             isChecked
                 ? prev.filter((id) => id !== item.id)