diff --git a/index.html b/index.html
index d6d1480..5a7b1a9 100644
--- a/index.html
+++ b/index.html
@@ -373,8 +373,10 @@ async function updateSensors() {
     const d = await r.json();
     const tempF = parseFloat(d.temperature);
     const tempC = ((tempF - 32) * 5/9).toFixed(1);
-    document.getElementById('s-temp').textContent = Math.round(tempF) + '°';
-    document.getElementById('s-temp').title = tempC + '°C';
+    const tempEl = document.getElementById('s-temp');
+    tempEl.textContent = Math.round(tempF) + '°';
+    tempEl.title = tempC + '°C';
+    tempEl.className = 'sensor-val' + (tempF < 73 || tempF > 76 ? ' crit' : '');
     
     const hum = parseFloat(d.humidity);
     const humEl = document.getElementById('s-hum');
@@ -384,7 +386,7 @@ async function updateSensors() {
     const co2 = parseInt(d.co2);
     const co2El = document.getElementById('s-co2');
     co2El.textContent = co2;
-    co2El.className = 'sensor-val' + (co2 > 1500 ? ' crit' : co2 > 1000 ? ' warn' : '');
+    co2El.className = 'sensor-val' + (co2 > 1100 ? ' crit' : co2 > 900 ? ' warn' : '');
   } catch(e) { console.error('Sensor fetch failed:', e); }
 }