diff --git a/web/app.js b/web/app.js
index da0cb11..18f64f5 100644
--- a/web/app.js
+++ b/web/app.js
@@ -15,7 +15,8 @@ let ws = null;
 let connected = false;
 
 // Live Manual-tab readouts (TempCtrl/Heater/Stirrer channels).
-let plotTempIst = null;
+let plotTempIst  = null;
+let plotTempSoll = null;
 let stirrerSpeedIst = 0;
 // Only the very first authoritative read after connecting is used to set
 // these particular sliders - thereafter they're purely user-controlled.
@@ -339,6 +340,22 @@ function updatePotVisualization() {
 	document.getElementById('thermo-temp-label').textContent =
 		plotTempIst !== null ? plotTempIst.toFixed(1) + ' °C' : '--';
 
+	// Soll temperature marker
+	const sollTick  = document.getElementById('thermo-soll-tick');
+	const sollLabel = document.getElementById('thermo-soll-label');
+	if (plotTempSoll !== null) {
+		const sollY = (tubeBottom - Math.max(0, Math.min(100, plotTempSoll)) / 100 * tubeLen).toFixed(1);
+		sollTick.setAttribute('y1', sollY);
+		sollTick.setAttribute('y2', sollY);
+		sollLabel.setAttribute('y', sollY);
+		sollLabel.textContent = plotTempSoll.toFixed(0) + '°';
+		sollTick.style.display  = '';
+		sollLabel.style.display = '';
+	} else {
+		sollTick.style.display  = 'none';
+		sollLabel.style.display = 'none';
+	}
+
 	// Water fill
 	const waterFillEl = document.getElementById('water-fill');
 	const waterWaveEl = document.getElementById('water-wave');
@@ -538,12 +555,14 @@ function onTempCtrlChanged(msg) {
 		if (key === 'Soll') {
 			const soll = msg.Soll;
 			if ('Temp' in soll) {
+				plotTempSoll = soll.Temp;
 				document.getElementById('lcd-temp-soll').textContent = soll.Temp.toFixed(1);
 				if (initialTempSollSync) {
 					document.getElementById('temp-soll').value = Math.round(soll.Temp);
 					initialTempSollSync = false;
 				}
 				document.getElementById('temp-soll-readout').textContent = document.getElementById('temp-soll').value;
+				updatePotVisualization();
 			}
 			if ('Rate' in soll) {
 				const rate = soll.Rate;
diff --git a/web/index.html b/web/index.html
index ebcbfcf..3f9f2bd 100644
--- a/web/index.html
+++ b/web/index.html
@@ -170,6 +170,12 @@
     <rect id="thermo-mercury" x="215" y="174" width="8" height="0"
           fill="#e0190a" clip-path="url(#tube-clip)"/>
 
+    <!-- Soll temperature marker (left side, orange, JS-positioned) -->
+    <line id="thermo-soll-tick" x1="203" y1="174" x2="212" y2="174"
+          stroke="#ff7043" stroke-width="2" stroke-linecap="round"/>
+    <text id="thermo-soll-label" x="201" y="174" font-size="9"
+          fill="#ff7043" text-anchor="end" dominant-baseline="middle"></text>
+
     <!-- Scale ticks -->
     <line x1="227" y1="28"  x2="236" y2="28"  stroke="#9e9e9e" stroke-width="1.5"/>
     <text x="239" y="32"  font-size="9" fill="#9e9e9e">100</text>