diff --git a/specs/Event_Processor_HLD_v2.md b/specs/Event_Processor_HLD_v2.md
index 200bd30..6d98303 100644
--- a/specs/Event_Processor_HLD_v2.md
+++ b/specs/Event_Processor_HLD_v2.md
@@ -30,32 +30,32 @@
 
 ```mermaid
 graph TD
-    subgraph Client Layer
+    subgraph ClientLayer [Client Layer]
         MA[Member App]
         MRA[Merchant App]
         EXT[External Systems]
     end
 
-    subgraph Gateway Layer
+    subgraph GatewayLayer [Gateway Layer]
         EP[event-processor-service<br/>Validate + Registry + Route]
         API[TP Sync API]
     end
 
-    subgraph Kafka
+    subgraph KafkaLayer [Kafka]
         ET[events-topic<br/>Direct Events / Reward Triggers]
         TT[tracking-topic<br/>Tracking Events]
         NT[noti-topic<br/>Notification Events]
         DLQ[dead-letter-topics]
     end
 
-    subgraph Core Services
+    subgraph CoreLayer [Core Services]
         TP[transaction-service<br/>Rule + Ledger + Inventory]
         ATTR[attribute-service<br/>State + Counters]
         NS[notification-service]
         MKT[marketing-service]
     end
 
-    subgraph Data Layer
+    subgraph DataLayer [Data Layer]
         DB_TP[(PostgreSQL<br/>Transaction DB)]
         DB_ATTR[(PostgreSQL<br/>Attribute DB)]
         REDIS[(Redis<br/>Cache)]
@@ -91,6 +91,12 @@ graph TD
     ET -. failed .-> DLQ
     TT -. failed .-> DLQ
     NT -. failed .-> DLQ
+
+    style ClientLayer fill:#e3f2fd,stroke:#1976d2,stroke-width:2px,stroke-dasharray: 5 5,color:#000
+    style GatewayLayer fill:#f3e5f5,stroke:#7b1fa2,stroke-width:2px,stroke-dasharray: 5 5,color:#000
+    style KafkaLayer fill:#fff3e0,stroke:#f57c00,stroke-width:2px,stroke-dasharray: 5 5,color:#000
+    style CoreLayer fill:#e8f5e9,stroke:#388e3c,stroke-width:2px,stroke-dasharray: 5 5,color:#000
+    style DataLayer fill:#efebe9,stroke:#5d4037,stroke-width:2px,stroke-dasharray: 5 5,color:#000
 ```
 
 #### 2.1. Event Categories