diff --git a/ui/index.html b/ui/index.html
index 6058620..931609b 100644
--- a/ui/index.html
+++ b/ui/index.html
@@ -195,11 +195,10 @@ window.updateIMU = function(data) {
   //   pitch → rotation.x   positive = nose up   (Three.js +x rotates -Z end upward ✓)
   //   roll  → -rotation.z  positive = right bank (Three.js +z is CCW from camera = left bank,
   //                         so negate to match right-bank-positive convention)
-  //   yaw   → -rotation.y  positive = CW from above (Three.js +y is CCW, sensor Z points down
-  //                         so gz+ = CW physical; negate so model spins correctly)
+  //   yaw   → +rotation.y  positive = CW from above (Three.js +y = CCW but gz sign matches)
   targetPitch = pitch * Math.PI / 180;
   targetRoll  = -roll * Math.PI / 180;   // negate: Three.js +z = left bank, we want right bank+
-  targetYaw   = -yaw  * Math.PI / 180;   // negate: Three.js +y = CCW, sensor gz+ = CW
+  targetYaw   =  yaw  * Math.PI / 180;   // no negate: measured yaw matches Three.js rotation.y
 
   document.getElementById('v-pitch').textContent = pitch.toFixed(1);
   document.getElementById('v-roll').textContent  = roll.toFixed(1);
@@ -274,9 +273,9 @@ function animate() {
 animate();
 
 window.resetYaw = function() {
-  // Capture current raw firmware yaw (before negate) as new zero reference.
-  // targetYaw = -(yawRaw - yawOffset) * pi/180, so yawRaw = yawOffset - targetYaw*180/pi
-  const currentFirmwareYaw = yawOffset - targetYaw * 180 / Math.PI;
+  // Capture current raw firmware yaw as new zero reference.
+  // targetYaw = (yawRaw - yawOffset) * pi/180, so yawRaw = yawOffset + targetYaw*180/pi
+  const currentFirmwareYaw = yawOffset + targetYaw * 180 / Math.PI;
   yawOffset = currentFirmwareYaw;
   targetYaw = 0;
 };