diff --git a/backend/nodes/acf_1d.py b/backend/nodes/acf_1d.py
index 0fc9961..bc9f70d 100644
--- a/backend/nodes/acf_1d.py
+++ b/backend/nodes/acf_1d.py
@@ -40,7 +40,7 @@ class ACF1D:
 
     DESCRIPTION = (
         "Compute the one-dimensional autocorrelation function of a line profile. "
-        "The output is symmetric about zero lag with the lag on the x-axis. "
+        "Only positive lags are output on the x-axis. "
         "The measurement table reports the dominant period from the first positive peak."
     )
 
@@ -54,6 +54,14 @@ class ACF1D:
         x_unit = profile.x_unit if isinstance(profile, LineData) else ""
         peak_lag = _first_positive_peak(acf_line.data, acf_line.x_axis)
 
+        mask = acf_line.x_axis > 0
+        acf_line = LineData(
+            data=acf_line.data[mask],
+            x_axis=acf_line.x_axis[mask],
+            x_unit=acf_line.x_unit,
+            y_unit=acf_line.y_unit,
+        )
+
         rows = []
         if peak_lag is not None:
             rows.append({"quantity": "Peak period", "value": peak_lag, "unit": x_unit})
diff --git a/frontend/src/styles.css b/frontend/src/styles.css
index 8b32c93..3c9ec0e 100644
--- a/frontend/src/styles.css
+++ b/frontend/src/styles.css
@@ -592,7 +592,6 @@ html, body, #root {
 
 .io-inline-widget input[type="text"],
 .io-inline-widget input[type="number"],
-.io-inline-widget input[type="color"],
 .io-inline-widget select {
   background: var(--bg-deep);
   color: var(--text-primary);
@@ -606,7 +605,6 @@ html, body, #root {
 
 .widget-row input[type="text"],
 .widget-row input[type="number"],
-.widget-row input[type="color"],
 .widget-row select {
   background: var(--bg-deep);
   color: var(--text-primary);
@@ -619,8 +617,31 @@ html, body, #root {
 }
 
 .widget-row input[type="color"] {
-  padding: 2px;
-  height: 24px;
+  appearance: none;
+  -webkit-appearance: none;
+  padding: 0;
+  width: 22px;
+  height: 22px;
+  border-radius: 50%;
+  border: 1.5px solid var(--border-default);
+  flex: none;
+  cursor: pointer;
+  overflow: hidden;
+  background: none;
+}
+
+.widget-row input[type="color"]::-webkit-color-swatch-wrapper {
+  padding: 0;
+}
+
+.widget-row input[type="color"]::-webkit-color-swatch {
+  border: none;
+  border-radius: 50%;
+}
+
+.widget-row input[type="color"]::-moz-color-swatch {
+  border: none;
+  border-radius: 50%;
 }
 
 .widget-row input[type="checkbox"] {