diff --git a/viz/app/item_page.js b/viz/app/item_page.js
index 9fe2285..ee8fd41 100644
--- a/viz/app/item_page.js
+++ b/viz/app/item_page.js
@@ -668,20 +668,24 @@ export async function renderItem($app, skuInput) {
   const colorMap = buildStoreColorMap(series.map((s) => s.label));
 
   const datasets = series.map((s) => {
-    const c = storeColor(s.label, colorMap);
+    const base = storeColor(s.label, colorMap);
+    const stroke = lighten(base, 0.25);
+  
     return {
       label: s.label,
       data: labels.map((d) => (s.points.has(d) ? s.points.get(d) : null)),
       spanGaps: false,
       tension: 0.15,
   
-      borderColor: c,
-      backgroundColor: c,
-      pointBackgroundColor: c,
-      pointBorderColor: c,
+      backgroundColor: base,
+      borderColor: stroke,
+      pointBackgroundColor: base,
+      pointBorderColor: stroke,
+      borderWidth: datasetStrokeWidth(base),
     };
   });
   
+  
   const ctx = $canvas.getContext("2d");
   CHART = new Chart(ctx, {
     type: "line",
diff --git a/viz/app/stats_page.js b/viz/app/stats_page.js
index c1f9b69..f20e24e 100644
--- a/viz/app/stats_page.js
+++ b/viz/app/stats_page.js
@@ -695,17 +695,20 @@ export async function renderStats($app) {
     const colorMap = buildStoreColorMap(stores); 
     
     const datasets = stores.map((s) => {
-        const c = storeColor(s, colorMap);
+        const base = storeColor(s, colorMap);
+        const stroke = lighten(base, 0.25);
+      
         return {
           label: displayStoreName(s),
           data: Array.isArray(seriesByStore[s]) ? seriesByStore[s] : labels.map(() => null),
           spanGaps: false,
           tension: 0.15,
       
-          borderColor: c,
-          backgroundColor: c,
-          pointBackgroundColor: c,
-          pointBorderColor: c,
+          backgroundColor: base,
+          borderColor: stroke,
+          pointBackgroundColor: base,
+          pointBorderColor: stroke,
+          borderWidth: datasetStrokeWidth(base),
         };
       });
       
diff --git a/viz/app/storeColors.js b/viz/app/storeColors.js
index 5e8092f..8765214 100644
--- a/viz/app/storeColors.js
+++ b/viz/app/storeColors.js
@@ -127,4 +127,39 @@ function normalizeId(s) {
   export function datasetPointRadius(color) {
     return isWhiteHex(color) ? 2.8 : 2.2;
   }
+  
+  function clamp(v, lo, hi) {
+    return Math.max(lo, Math.min(hi, v));
+  }
+  
+  function hexToRgb(hex) {
+    const m = String(hex).replace("#", "");
+    if (m.length !== 6) return null;
+    const n = parseInt(m, 16);
+    return {
+      r: (n >> 16) & 255,
+      g: (n >> 8) & 255,
+      b: n & 255,
+    };
+  }
+  
+  function rgbToHex({ r, g, b }) {
+    const h = (x) => clamp(Math.round(x), 0, 255).toString(16).padStart(2, "0");
+    return `#${h(r)}${h(g)}${h(b)}`;
+  }
+  
+  // lighten by mixing with white (amount 0–1)
+  export function lighten(hex, amount = 0.25) {
+    const rgb = hexToRgb(hex);
+    if (!rgb) return hex;
+    return rgbToHex({
+      r: rgb.r + (255 - rgb.r) * amount,
+      g: rgb.g + (255 - rgb.g) * amount,
+      b: rgb.b + (255 - rgb.b) * amount,
+    });
+  }
+  
+  export function datasetStrokeWidth(color) {
+    return String(color).toUpperCase() === "#FFFFFF" ? 2.5 : 1.5;
+  }
   
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