diff --git a/site/src/components/ActivityCharts.svelte b/site/src/components/ActivityCharts.svelte
index 3a1114d..44608a6 100644
--- a/site/src/components/ActivityCharts.svelte
+++ b/site/src/components/ActivityCharts.svelte
@@ -147,9 +147,9 @@
     };
   }
 
-  // ── Reference lines (avg, P20, P80) — speed, cadence, and power ────────
+  // ── Reference lines (avg, P20, P80) — speed, cadence, power, hr ────────
   function refStats(tab: Tab, vals: number[]) {
-    if (tab !== 'speed' && tab !== 'cadence' && tab !== 'power') return null;
+    if (tab !== 'speed' && tab !== 'cadence' && tab !== 'power' && tab !== 'hr') return null;
     const moving = vals.filter(v => v > 0);
     if (moving.length < 5) return null;
     const avg = moving.reduce((a, b) => a + b, 0) / moving.length;
@@ -236,7 +236,8 @@
             { xv: xEnd, yv: ref.p20, label: `P20 ${Math.round(ref.p20)}` },
             { xv: xEnd, yv: ref.p80, label: `P80 ${Math.round(ref.p80)}` },
           ],
-          { x: 'xv', y: 'yv', text: 'label', textAnchor: 'end', dx: -4, dy: -6, fill: tc.axis, fontSize: 10 },
+          { x: 'xv', y: 'yv', text: 'label', textAnchor: 'end', dx: -4, dy: -6,
+            fill: tc.tooltipFg, stroke: tc.tooltipBg, strokeWidth: 3, fontSize: 11 },
         ),
       );
     }