diff --git a/apps/web/src/pages/EntityDetail/ActivityChart.tsx b/apps/web/src/pages/EntityDetail/ActivityChart.tsx
index 542e81c..811124b 100644
--- a/apps/web/src/pages/EntityDetail/ActivityChart.tsx
+++ b/apps/web/src/pages/EntityDetail/ActivityChart.tsx
@@ -24,7 +24,7 @@ interface ActivityChartProps {
 }
 
 const CHART_HEIGHT = 260
-const MARGIN = { bottom: 30, left: 50, right: 60, top: 10 }
+const MARGIN = { bottom: 30, left: 50, right: 110, top: 10 }
 
 /** Hypnogram Y-axis labels in display order (top to bottom). */
 const HYPNOGRAM_LABELS = ['Awake', 'REM', 'Light', 'Deep']
@@ -95,12 +95,14 @@ const drawLineOverlay = (
   unit: string,
   axisSide: 'left' | 'right',
   axisOffset: number = 0,
+  forceZeroMin: boolean = false,
 ) => {
   const yExtent = d3.extent(data, (d) => d[1]) as [number, number]
   const padding = (yExtent[1] - yExtent[0]) * 0.1 || 5
+  const yMin = forceZeroMin && yExtent[0] >= 0 ? 0 : yExtent[0] - padding
   const yScale = d3
     .scaleLinear()
-    .domain([yExtent[0] - padding, yExtent[1] + padding])
+    .domain([yMin, yExtent[1] + padding])
     .range([innerHeight, 0])
 
   if (axisSide === 'right') {
@@ -223,7 +225,7 @@ export const ActivityChart = ({
       const hrVisible = hasData(hrData)
       const axisSide = hrVisible || hasHypnogram ? 'right' : 'left'
       const offset = axisSide === 'right' && hrVisible ? 45 : 0
-      drawLineOverlay(g, xScale, innerWidth, innerHeight, hrvData, '#14b8a6', 'ms', axisSide, offset)
+      drawLineOverlay(g, xScale, innerWidth, innerHeight, hrvData, '#14b8a6', 'ms', axisSide, offset, true)
     }
 
     // Tooltip crosshair and interaction overlay
diff --git a/apps/web/src/pages/EntityDetail/EditableActivityFields.tsx b/apps/web/src/pages/EntityDetail/EditableActivityFields.tsx
index fc4428d..44b7638 100644
--- a/apps/web/src/pages/EntityDetail/EditableActivityFields.tsx
+++ b/apps/web/src/pages/EntityDetail/EditableActivityFields.tsx
@@ -75,17 +75,16 @@ export const EditableActivityFields = ({
             <span class="field-label">{durationLabel}</span>
             <span class="field-value">{draftDuration}</span>
           </div>
-          <div class="field-row">
-            <span class="field-label">Notes</span>
-            <span class="field-value">
-              <textarea
-                class="edit-notes-input"
-                value={draft.notes}
-                onInput={(e) => onDraftChange({ ...draft, notes: (e.target as HTMLTextAreaElement).value })}
-                rows={3}
-              />
-            </span>
-          </div>
+        </div>
+
+        <div class="edit-notes-block">
+          <span class="field-label">Notes</span>
+          <textarea
+            class="edit-notes-input"
+            value={draft.notes}
+            onInput={(e) => onDraftChange({ ...draft, notes: (e.target as HTMLTextAreaElement).value })}
+            rows={3}
+          />
         </div>
       </>
     )
diff --git a/apps/web/src/pages/EntityDetail/ExerciseDetail.tsx b/apps/web/src/pages/EntityDetail/ExerciseDetail.tsx
index 16b792f..82f2ff6 100644
--- a/apps/web/src/pages/EntityDetail/ExerciseDetail.tsx
+++ b/apps/web/src/pages/EntityDetail/ExerciseDetail.tsx
@@ -1,7 +1,8 @@
 /**
  * Exercise-specific detail view with HR chart and HR zone bar.
  */
-import { Activity } from '../../state/api'
+import { useQuery } from '@tanstack/react-query'
+import { Activity, fetchMetricTimeSeries } from '../../state/api'
 import { ActivityChart } from './ActivityChart'
 import { type ActivityDraft, EditableActivityFields } from './EditableActivityFields'
 
@@ -64,6 +65,17 @@ export const ExerciseDetail = ({
     | string
     | undefined
 
+  const caloriesQuery = useQuery({
+    queryFn: () => fetchMetricTimeSeries('calories_active', displayStart, displayEnd),
+    queryKey: ['detail-calories', displayStart.toISOString(), displayEnd.toISOString()],
+    staleTime: 5 * 60 * 1000,
+  })
+
+  const totalCalories =
+    caloriesQuery.data && caloriesQuery.data.length > 0 ?
+      Math.round(caloriesQuery.data.reduce((sum, [, val]) => sum + val, 0))
+    : undefined
+
   return (
     <>
       <div class="entity-info">
@@ -82,6 +94,15 @@ export const ExerciseDetail = ({
           onDraftChange={onDraftChange}
         />
 
+        {!isEditing && totalCalories !== undefined && (
+          <div class="entity-fields">
+            <div class="field-row">
+              <span class="field-label">Active Calories</span>
+              <span class="field-value">{totalCalories} kcal</span>
+            </div>
+          </div>
+        )}
+
         {!isEditing && activity.avg_hrv !== undefined && (
           <div class="entity-fields">
             <div class="field-row">
@@ -96,7 +117,7 @@ export const ExerciseDetail = ({
 
       {/* HR chart with overlays */}
       <div class="detail-grid-full">
-        <ActivityChart start={displayStart} end={displayEnd} showHrDefault={true} />
+        <ActivityChart start={displayStart} end={displayEnd} showHrDefault={true} showHrvDefault={true} />
       </div>
     </>
   )
diff --git a/apps/web/src/pages/EntityDetail/index.tsx b/apps/web/src/pages/EntityDetail/index.tsx
index 8cbacd8..3b9fce5 100644
--- a/apps/web/src/pages/EntityDetail/index.tsx
+++ b/apps/web/src/pages/EntityDetail/index.tsx
@@ -449,9 +449,9 @@ export const EntityDetail = () => {
   return (
     <div class="entity-detail-page">
       <div class="entity-detail-header">
-        <a href="/day" class="back-link">
-          Back to Day View
-        </a>
+        <button type="button" class="back-link back-link-btn" onClick={() => history.back()}>
+          Back
+        </button>
       </div>
       <EntityContent entityType={entityType} entityId={entityId} />
     </div>
diff --git a/apps/web/src/pages/EntityDetail/style.css b/apps/web/src/pages/EntityDetail/style.css
index d12451e..47c714c 100644
--- a/apps/web/src/pages/EntityDetail/style.css
+++ b/apps/web/src/pages/EntityDetail/style.css
@@ -20,6 +20,14 @@
   text-decoration: underline;
 }
 
+.back-link-btn {
+  background: none;
+  border: none;
+  padding: 0;
+  cursor: pointer;
+  font: inherit;
+}
+
 /* Deleted banner */
 .deleted-banner {
   display: flex;
@@ -617,6 +625,13 @@
   box-shadow: 0 0 0 2px rgba(103, 58, 184, 0.2);
 }
 
+.edit-notes-block {
+  margin-top: 0.5rem;
+  display: flex;
+  flex-direction: column;
+  gap: 0.25rem;
+}
+
 .edit-notes-input {
   width: 100%;
   padding: 0.375rem 0.5rem;