diff --git a/src/components/AnnotationGroupItem.tsx b/src/components/AnnotationGroupItem.tsx
index cc80dfbb..caec9519 100644
--- a/src/components/AnnotationGroupItem.tsx
+++ b/src/components/AnnotationGroupItem.tsx
@@ -6,7 +6,6 @@ import {
   Col,
   Divider,
   InputNumber,
-  Menu,
   Popover,
   Row,
   Select,
@@ -564,41 +563,25 @@ class AnnotationGroupItem extends React.Component<
     const color = this.getCurrentColor()
     const isBadgeVisible =
       this.state.isVisible && this.state.currentStyle.measurement === null
-    const {
-      annotationGroup,
-      defaultStyle,
-      isVisible,
-      metadata,
-      onVisibilityChange,
-      onStyleChange,
-      onAnnotationGroupClick,
-      ...otherProps
-    } = this.props
     return (
-      <Menu.Item
-        style={{ height: '100%', paddingLeft: '3px' }}
-        key={this.props.annotationGroup.uid}
-        {...otherProps}
-      >
-        <Space align="start">
-          <div style={{ paddingLeft: '14px' }}>
-            <AnnotationGroupControls
-              isVisible={this.props.isVisible}
-              onVisibilityChange={this.handleVisibilityChange}
-              settings={settings}
-              color={this.state.currentStyle.color ?? [255, 255, 255]}
-            />
-          </div>
-          <AnnotationGroupBadgeDescription
-            onClick={this.handleAnnotationGroupClick}
-            annotationGroup={this.props.annotationGroup}
-            isBadgeVisible={isBadgeVisible}
-            color={color}
-            label={this.props.annotationGroup.label}
-            attributes={attributes}
+      <Space align="start">
+        <div style={{ paddingLeft: '14px' }}>
+          <AnnotationGroupControls
+            isVisible={this.props.isVisible}
+            onVisibilityChange={this.handleVisibilityChange}
+            settings={settings}
+            color={this.state.currentStyle.color ?? [255, 255, 255]}
           />
-        </Space>
-      </Menu.Item>
+        </div>
+        <AnnotationGroupBadgeDescription
+          onClick={this.handleAnnotationGroupClick}
+          annotationGroup={this.props.annotationGroup}
+          isBadgeVisible={isBadgeVisible}
+          color={color}
+          label={this.props.annotationGroup.label}
+          attributes={attributes}
+        />
+      </Space>
     )
   }
 }
diff --git a/src/components/AnnotationGroupList.tsx b/src/components/AnnotationGroupList.tsx
index 05cf29c4..afcb1c3b 100644
--- a/src/components/AnnotationGroupList.tsx
+++ b/src/components/AnnotationGroupList.tsx
@@ -1,3 +1,4 @@
+import type { MenuProps } from 'antd'
 import { Menu, Switch } from 'antd'
 // skipcq: JS-C1003
 import type * as dcmjs from 'dcmjs'
@@ -67,21 +68,26 @@ class AnnotationGroupList extends React.Component<
   }
 
   render(): React.ReactNode {
-    const items = this.props.annotationGroups.map((annotationGroup, _index) => {
-      const uid = annotationGroup.uid
-      return (
-        <AnnotationGroupItem
-          key={annotationGroup.uid}
-          annotationGroup={annotationGroup}
-          onAnnotationGroupClick={this.props.onAnnotationGroupClick}
-          metadata={this.props.metadata[uid]}
-          isVisible={this.props.visibleAnnotationGroupUIDs.has(uid)}
-          defaultStyle={this.props.defaultAnnotationGroupStyles[uid]}
-          onVisibilityChange={this.props.onAnnotationGroupVisibilityChange}
-          onStyleChange={this.props.onAnnotationGroupStyleChange}
-        />
-      )
-    })
+    const items: MenuProps['items'] = this.props.annotationGroups.map(
+      (annotationGroup) => {
+        const uid = annotationGroup.uid
+        return {
+          key: uid,
+          style: { height: '100%', paddingLeft: '3px' },
+          label: (
+            <AnnotationGroupItem
+              annotationGroup={annotationGroup}
+              onAnnotationGroupClick={this.props.onAnnotationGroupClick}
+              metadata={this.props.metadata[uid]}
+              isVisible={this.props.visibleAnnotationGroupUIDs.has(uid)}
+              defaultStyle={this.props.defaultAnnotationGroupStyles[uid]}
+              onVisibilityChange={this.props.onAnnotationGroupVisibilityChange}
+              onStyleChange={this.props.onAnnotationGroupStyleChange}
+            />
+          ),
+        }
+      },
+    )
 
     return (
       <>
@@ -100,7 +106,7 @@ class AnnotationGroupList extends React.Component<
             unCheckedChildren={<FaEyeSlash />}
           />
         </div>
-        <Menu selectable={false}>{items}</Menu>
+        <Menu selectable={false} items={items} />
       </>
     )
   }
diff --git a/src/components/Header.tsx b/src/components/Header.tsx
index 2337f056..1bc9a225 100644
--- a/src/components/Header.tsx
+++ b/src/components/Header.tsx
@@ -9,7 +9,6 @@ import {
   UserOutlined,
 } from '@ant-design/icons'
 import {
-  Badge,
   Col,
   Collapse,
   Dropdown,
@@ -86,6 +85,59 @@ const aboutModalStyles: Record<string, React.CSSProperties> = {
   },
 }
 
+/**
+ * Static count pill that avoids antd Badge → rc-motion `findDOMNode`
+ * (deprecated under React Strict Mode).
+ */
+function HeaderCountBadge({
+  count,
+  color = '#ff4d4f',
+  zIndex,
+  children,
+}: {
+  count: number
+  color?: string
+  zIndex?: number
+  children?: React.ReactNode
+}): JSX.Element {
+  const pill =
+    count > 0 ? (
+      <sup
+        style={{
+          position: children != null ? 'absolute' : 'relative',
+          top: children != null ? -4 : undefined,
+          right: children != null ? -8 : undefined,
+          zIndex,
+          display: 'inline-block',
+          minWidth: 16,
+          height: 16,
+          padding: '0 5px',
+          borderRadius: 8,
+          background: color,
+          color: '#fff',
+          fontSize: 10,
+          lineHeight: '16px',
+          textAlign: 'center',
+          boxShadow: '0 0 0 1px #fff',
+          verticalAlign: children != null ? undefined : 'middle',
+        }}
+      >
+        {count > 99 ? '99+' : count}
+      </sup>
+    ) : null
+
+  if (children == null) {
+    return <>{pill}</>
+  }
+
+  return (
+    <span style={{ position: 'relative', display: 'inline-block' }}>
+      {children}
+      {pill}
+    </span>
+  )
+}
+
 interface HeaderProps extends RouteComponentProps {
   app: {
     name: string
@@ -421,11 +473,14 @@ class Header extends React.Component<HeaderProps, HeaderState> {
     const { Panel } = Collapse
 
     const showErrorCount = (errcount: number): JSX.Element => (
-      <Badge count={errcount} />
+      <HeaderCountBadge count={errcount} />
     )
 
     const showWarningCount = (warncount: number): JSX.Element => (
-      <Badge color={warncount > 0 ? 'green' : undefined} count={warncount} />
+      <HeaderCountBadge
+        count={warncount}
+        color={warncount > 0 ? '#52c41a' : '#ff4d4f'}
+      />
     )
 
     Modal.info({
@@ -612,19 +667,63 @@ class Header extends React.Component<HeaderProps, HeaderState> {
     )
 
     const debugButton = (
-      <Badge count={this.state.errorObj.length} style={{ zIndex: 1000 }}>
-        <Badge
-          color={this.state.warnings.length > 0 ? 'green' : undefined}
-          count={this.state.warnings.length}
-          style={{ zIndex: 1001 }}
-        >
-          <Button
-            icon={BugOutlined}
-            tooltip="Debug info"
-            onClick={this.handleDebugButtonClick}
-          />
-        </Badge>
-      </Badge>
+      <span style={{ position: 'relative', display: 'inline-block' }}>
+        <Button
+          icon={BugOutlined}
+          tooltip="Debug info"
+          onClick={this.handleDebugButtonClick}
+        />
+        {this.state.warnings.length > 0 ? (
+          <sup
+            style={{
+              position: 'absolute',
+              top: -4,
+              right: this.state.errorObj.length > 0 ? 10 : -8,
+              zIndex: 1001,
+              display: 'inline-block',
+              minWidth: 16,
+              height: 16,
+              padding: '0 5px',
+              borderRadius: 8,
+              background: '#52c41a',
+              color: '#fff',
+              fontSize: 10,
+              lineHeight: '16px',
+              textAlign: 'center',
+              boxShadow: '0 0 0 1px #fff',
+            }}
+          >
+            {this.state.warnings.length > 99
+              ? '99+'
+              : this.state.warnings.length}
+          </sup>
+        ) : null}
+        {this.state.errorObj.length > 0 ? (
+          <sup
+            style={{
+              position: 'absolute',
+              top: -4,
+              right: -8,
+              zIndex: 1000,
+              display: 'inline-block',
+              minWidth: 16,
+              height: 16,
+              padding: '0 5px',
+              borderRadius: 8,
+              background: '#ff4d4f',
+              color: '#fff',
+              fontSize: 10,
+              lineHeight: '16px',
+              textAlign: 'center',
+              boxShadow: '0 0 0 1px #fff',
+            }}
+          >
+            {this.state.errorObj.length > 99
+              ? '99+'
+              : this.state.errorObj.length}
+          </sup>
+        ) : null}
+      </span>
     )
 
     const showDicomTagBrowser = DICOM_TAG_BROWSER_PATHS.some((path) =>
diff --git a/src/components/SlideItem.tsx b/src/components/SlideItem.tsx
index d79b870b..3d4fb91f 100644
--- a/src/components/SlideItem.tsx
+++ b/src/components/SlideItem.tsx
@@ -1,4 +1,4 @@
-import { Menu, Typography } from 'antd'
+import { Typography } from 'antd'
 // skipcq: JS-C1003
 import * as dmv from 'dicom-microscopy-viewer'
 import React from 'react'
@@ -106,60 +106,51 @@ class SlideItem extends React.Component<SlideItemProps, SlideItemState> {
       return <FaSpinner />
     }
 
-    /* Properties need to be propagated down to Menu.Item:
-     * https://github.com/react-component/menu/issues/142
-     */
     return (
-      <Menu.Item
-        style={{ height: '100%' }}
-        key={this.props.slide.seriesInstanceUIDs[0]}
-        {...this.props}
+      <Description
+        header={this.props.slide.containerIdentifier}
+        attributes={attributes}
+        selectable
       >
-        <Description
-          header={this.props.slide.containerIdentifier}
-          attributes={attributes}
-          selectable
-        >
-          <div style={{ position: 'relative', height: '100px' }}>
-            {this.props.slide.overviewImages.length > 0 ||
-            this.props.slide.thumbnailImages.length > 0 ? (
-              <div ref={this.overviewViewportRef} style={{ height: '100%' }} />
-            ) : (
-              <div
-                style={{
-                  height: '100%',
-                  textAlign: 'center',
-                  display: 'flex',
-                  alignItems: 'center',
-                  justifyContent: 'center',
-                  fontSize: '1.5rem',
-                  fontWeight: 300,
-                  color: '#8F9BA8',
-                  letterSpacing: '0.1em',
-                }}
-              >
-                SM
-              </div>
-            )}
-            <ValidationWarning slide={this.props.slide} />
-          </div>
-          {this.props.slide.seriesDescription !== undefined &&
-          this.props.slide.seriesDescription !== null &&
-          this.props.slide.seriesDescription !== '' ? (
-            <Typography.Text
-              type="secondary"
+        <div style={{ position: 'relative', height: '100px' }}>
+          {this.props.slide.overviewImages.length > 0 ||
+          this.props.slide.thumbnailImages.length > 0 ? (
+            <div ref={this.overviewViewportRef} style={{ height: '100%' }} />
+          ) : (
+            <div
               style={{
-                display: 'block',
-                marginTop: 4,
-                fontSize: '0.75rem',
-                lineHeight: 1.2,
+                height: '100%',
+                textAlign: 'center',
+                display: 'flex',
+                alignItems: 'center',
+                justifyContent: 'center',
+                fontSize: '1.5rem',
+                fontWeight: 300,
+                color: '#8F9BA8',
+                letterSpacing: '0.1em',
               }}
             >
-              {this.props.slide.seriesDescription}
-            </Typography.Text>
-          ) : null}
-        </Description>
-      </Menu.Item>
+              SM
+            </div>
+          )}
+          <ValidationWarning slide={this.props.slide} />
+        </div>
+        {this.props.slide.seriesDescription !== undefined &&
+        this.props.slide.seriesDescription !== null &&
+        this.props.slide.seriesDescription !== '' ? (
+          <Typography.Text
+            type="secondary"
+            style={{
+              display: 'block',
+              marginTop: 4,
+              fontSize: '0.75rem',
+              lineHeight: 1.2,
+            }}
+          >
+            {this.props.slide.seriesDescription}
+          </Typography.Text>
+        ) : null}
+      </Description>
     )
   }
 }
diff --git a/src/components/SlideList.tsx b/src/components/SlideList.tsx
index e5e9601a..4c3aa482 100644
--- a/src/components/SlideList.tsx
+++ b/src/components/SlideList.tsx
@@ -1,3 +1,4 @@
+import type { MenuProps } from 'antd'
 import { Menu } from 'antd'
 import React from 'react'
 
@@ -35,32 +36,16 @@ class SlideList extends React.Component<SlideListProps, SlideListState> {
   }
 
   render(): React.ReactNode {
-    const slideList = this.props.metadata
-    const slideItemList = []
-    for (let i = 0; i < slideList.length; ++i) {
-      const slide = slideList[i]
-      const slideItem = (
-        <SlideItem
-          key={slide.seriesInstanceUIDs[0]}
-          slide={slide}
-          clients={this.props.clients}
-        />
-      )
-
-      slideItemList.push(slideItem)
-    }
+    const items: MenuProps['items'] = this.props.metadata.map((slide) => {
+      const key = slide.seriesInstanceUIDs[0]
+      return {
+        key,
+        style: { height: '100%' },
+        label: <SlideItem slide={slide} clients={this.props.clients} />,
+      }
+    })
 
-    const handleMenuItemSelection = ({
-      key,
-      keyPath: _keyPath,
-      domEvent: _domEvent,
-      selectedKeys: _selectedKeys,
-    }: {
-      key: React.ReactText
-      keyPath: React.ReactText[]
-      domEvent: React.MouseEvent<HTMLElement> | React.KeyboardEvent<HTMLElement>
-      selectedKeys?: React.ReactText[]
-    }): void => {
+    const handleMenuItemSelection: MenuProps['onSelect'] = ({ key }) => {
       console.info(`select slide "${key}"`)
       this.setState({ selectedSeriesInstanceUID: key.toString() })
       this.props.onSeriesSelection({ seriesInstanceUID: key.toString() })
@@ -81,9 +66,8 @@ class SlideList extends React.Component<SlideListProps, SlideListState> {
         onSelect={handleMenuItemSelection}
         mode="inline"
         inlineIndent={0}
-      >
-        {slideItemList}
-      </Menu>
+        items={items}
+      />
     )
   }
 }