polish(network): visual refinements across node, edge, and panel components

- DeviceNode: flat bg-card (no surface gradient), darker icon plate inset,
  correct text-muted token for category label
- GroupNode: label pill gets bg-card/90 background so it reads against canvas
- ConnectionEdge: label now has border + bg-card so it doesn't float invisible
- BaseHandle: tightened to 12px with accent-toned border
- NodeStatusIndicator: glow reduced to 0.15 opacity (design system compliant)
- ContextMenu: Ungroup now uses Ungroup icon instead of BoxSelect
- DeviceToolbar: group type icons coloured with semantic palette
- PropertiesPanel: empty state gets icon tile + cleaner copy hierarchy
- DiagramEditor: shortcut ? button repositioned above MiniMap, accent hover
- NetworkDiagrams list: card thumbnail placeholder uses dot-grid pattern,
  card menu gets icons and divider before destructive action

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/network/ContextMenu.tsx

@@ -1,6 +1,6 @@
 import { useEffect, useRef } from 'react'
 import {
-  Copy, CopyPlus, Trash2, ClipboardPaste, BoxSelect, Maximize2, BringToFront, SendToBack,
+  Copy, CopyPlus, Trash2, ClipboardPaste, BoxSelect, Ungroup, Maximize2, BringToFront, SendToBack,
   AlignStartVertical, AlignCenterHorizontal, AlignEndVertical,
   AlignStartHorizontal, AlignCenterVertical, AlignEndHorizontal,
   AlignHorizontalSpaceAround, AlignVerticalSpaceAround,
@@ -168,7 +168,7 @@ export function ContextMenu({
           )}
           {canUngroup && (
             <button onClick={() => { onUngroupSelection?.(); onClose() }} className="flex w-full items-center gap-2 px-3 py-2 text-xs text-primary hover:bg-elevated">
-              <BoxSelect size={13} /> <span>Ungroup</span>
+              <Ungroup size={13} /> <span>Ungroup</span>
             </button>
           )}
         </>

frontend/src/components/network/edges/ConnectionEdge.tsx

@@ -54,7 +54,7 @@ function ConnectionEdgeComponent(props: EdgeProps) {
       {props.label && (
         <EdgeLabelRenderer>
           <div
-            className="nodrag nopan rounded bg-page px-1.5 py-0.5 text-[10px] text-muted-foreground"
+            className="nodrag nopan rounded border border-default bg-card px-1.5 py-0.5 text-[10px] text-muted-foreground shadow-sm"
             style={{
               position: 'absolute',
               transform: `translate(-50%, -50%) translate(${labelX}px, ${labelY}px)`,

frontend/src/components/network/nodes/DeviceNode.tsx

@@ -84,7 +84,7 @@ function DeviceNodeComponent({ id, data, selected, width, height }: NodeProps) {
       <NodeStatusIndicator status={status}>
         <NodeTooltip>
           <NodeTooltipTrigger>
-            <BaseNode className="group h-full w-full bg-gradient-to-b from-card via-card to-page/70">
+            <BaseNode className="group h-full w-full bg-card">
               <div className={cn('pointer-events-none absolute inset-x-0 top-0 h-10 bg-gradient-to-b opacity-80', surfaceClass)} />
               <BaseNodeHeader className="flex h-full flex-col items-center justify-center gap-2 px-2 py-3">
                 <div
@@ -94,7 +94,7 @@ function DeviceNodeComponent({ id, data, selected, width, height }: NodeProps) {
                   )}
                   style={{ width: iconPlateSize, height: iconPlateSize }}
                 >
-                  <div className="absolute inset-[4px] rounded-[10px] border border-white/6 bg-page/55" />
+                  <div className="absolute inset-[4px] rounded-[10px] border border-white/[0.06] bg-sidebar/50" />
                   <div className="relative z-10">
                     <Icon size={iconPx} style={{ color }} />
                   </div>
@@ -135,7 +135,7 @@ function DeviceNodeComponent({ id, data, selected, width, height }: NodeProps) {
                 )}
                 <span
                   style={{ fontSize: metaPx }}
-                  className="text-[9px] uppercase tracking-[0.16em] text-muted-foreground/80"
+                  className="text-[9px] uppercase tracking-[0.16em] text-muted"
                 >
                   {CATEGORY_LABELS[category] ?? nodeData.deviceType.replace(/-/g, ' ')}
                 </span>

frontend/src/components/network/nodes/GroupNode.tsx

@@ -51,7 +51,7 @@ const GroupNodeComponent = ({ data, selected, id }: NodeProps) => {
           boxSizing: 'border-box',
         }}
       >
-        <div className="absolute top-0 left-0 -translate-y-full pb-0.5 pl-1">
+        <div className="absolute top-0 left-2 -translate-y-full pb-0.5">
           {editing ? (
             <input
               ref={inputRef}
@@ -62,12 +62,12 @@ const GroupNodeComponent = ({ data, selected, id }: NodeProps) => {
                 if (e.key === 'Enter' || e.key === 'Escape') handleLabelCommit()
                 e.stopPropagation()
               }}
-              className="text-[11px] font-medium bg-transparent border-none outline-none text-primary min-w-[40px] max-w-[200px]"
+              className="rounded-sm px-1.5 py-0.5 text-[11px] font-semibold bg-card/90 border-none outline-none min-w-[40px] max-w-[200px]"
               style={{ color }}
             />
           ) : (
             <span
-              className="text-[11px] font-medium cursor-text select-none"
+              className="inline-block rounded-sm bg-card/90 px-1.5 py-0.5 text-[11px] font-semibold cursor-text select-none tracking-wide"
               style={{ color }}
               onDoubleClick={() => setEditing(true)}
             >

frontend/src/components/network/panels/DeviceToolbar.tsx

@@ -151,22 +151,22 @@ export function DeviceToolbar({ deviceTypes, onDeviceTypesChange }: DeviceToolba
         </div>
         <div className="flex flex-col gap-0.5">
           {[
-            { slug: 'subnet', label: 'Subnet' },
-            { slug: 'vlan', label: 'VLAN' },
-            { slug: 'site', label: 'Site' },
-            { slug: 'dmz', label: 'DMZ' },
+            { slug: 'subnet', label: 'Subnet', color: '#60a5fa' },
+            { slug: 'vlan',   label: 'VLAN',   color: '#a78bfa' },
+            { slug: 'site',   label: 'Site',   color: '#34d399' },
+            { slug: 'dmz',    label: 'DMZ',    color: '#f87171' },
           ].map(item => (
             <div
               key={item.slug}
               draggable
               onDragStart={e => {
-                e.dataTransfer.setData('application/reactflow-group', JSON.stringify(item))
+                e.dataTransfer.setData('application/reactflow-group', JSON.stringify({ slug: item.slug, label: item.label }))
                 e.dataTransfer.effectAllowed = 'move'
               }}
               className="flex cursor-grab items-center gap-2 rounded px-2 py-1.5 text-xs text-primary hover:bg-elevated active:cursor-grabbing active:scale-[0.98] transition-transform"
             >
               <GripVertical size={12} className="shrink-0 text-muted-foreground/50" />
-              <LayoutGrid size={14} className="text-muted-foreground" />
+              <LayoutGrid size={14} style={{ color: item.color }} />
               <span>{item.label}</span>
             </div>
           ))}

frontend/src/components/network/panels/PropertiesPanel.tsx

@@ -4,7 +4,7 @@ import {
   AlignStartVertical, AlignCenterHorizontal, AlignEndVertical,
   AlignStartHorizontal, AlignCenterVertical, AlignEndHorizontal,
   AlignHorizontalSpaceAround, AlignVerticalSpaceAround,
-  BoxSelect, Ungroup,
+  BoxSelect, Ungroup, MousePointer,
 } from 'lucide-react'
 import { cn } from '@/lib/utils'
 import type { DeviceProperties, DiagramEdge } from '@/types'
@@ -235,12 +235,15 @@ export function PropertiesPanel({
 
   if (!selectedNode && !selectedEdge) {
     return (
-      <div className="flex h-full w-[260px] flex-col items-center justify-center border-l border-default bg-sidebar px-4">
-        <p className="text-center text-xs text-muted-foreground">
-          Select a device or connection to edit its properties
+      <div className="flex h-full w-[260px] flex-col items-center justify-center border-l border-default bg-sidebar px-6">
+        <div className="mb-3 flex h-9 w-9 items-center justify-center rounded-lg border border-default bg-elevated text-muted-foreground">
+          <MousePointer size={15} />
+        </div>
+        <p className="text-center text-xs font-medium text-muted-foreground">
+          Select a device or connection
         </p>
-        <p className="mt-1 text-center text-[10px] text-muted-foreground/60">
-          Hover a device to preview its info
+        <p className="mt-1 text-center text-[10px] text-muted-foreground/50 leading-relaxed">
+          Properties appear here. Hover a device to see a quick summary.
         </p>
       </div>
     )

frontend/src/components/network/ui/base-handle.tsx

@@ -9,7 +9,7 @@ export function BaseHandle({ className, children, ...props }: ComponentProps<typ
     <Handle
       {...props}
       className={cn(
-        'h-[14px] w-[14px] rounded-full border border-default bg-elevated transition-opacity',
+        'h-3 w-3 rounded-full border border-accent/60 bg-card transition-opacity',
         'opacity-0 group-hover:opacity-100 group-focus-within:opacity-100',
         '[.rf-connect-mode_&]:opacity-100',
         className,

frontend/src/components/network/ui/node-status-indicator.tsx

@@ -11,9 +11,9 @@ const STATUS_BORDER_COLORS: Record<NodeStatus, string> = {
 }
 
 const STATUS_GLOW: Record<NodeStatus, string> = {
-  online: 'shadow-[0_0_8px_rgba(52,211,153,0.3)]',
-  offline: 'shadow-[0_0_8px_rgba(248,113,113,0.3)]',
-  degraded: 'shadow-[0_0_8px_rgba(250,204,21,0.3)]',
+  online: 'shadow-[0_0_6px_rgba(52,211,153,0.15)]',
+  offline: 'shadow-[0_0_6px_rgba(248,113,113,0.15)]',
+  degraded: 'shadow-[0_0_6px_rgba(250,204,21,0.15)]',
   unknown: '',
 }