Fix dark mode diagram visibility and CSS syntax error

Bug fixes:
- Fixed architecture diagram text being invisible in dark mode by removing
  hardcoded color fills that overrode theme colors
- Added missing semicolon after 'color: white' in .cta-primary style to
  prevent CSS parsing issues

Author: shah95rukh

docs/docs/learn/architecture.mdx

@@ -55,13 +55,6 @@ graph TB
     Client1 ---|"One-to-one<br/>connection"| Server1
     Client2 ---|"One-to-one<br/>connection"| Server2
     Client3 ---|"One-to-one<br/>connection"| Server3
-
-    style Client1 fill:#e1f5fe
-    style Client2 fill:#e1f5fe
-    style Client3 fill:#e1f5fe
-    style Server1 fill:#f3e5f5
-    style Server2 fill:#f3e5f5
-    style Server3 fill:#f3e5f5
 ```
 
 Note that **MCP server** refers to the program that serves context data, regardless of

docs/style.css

@@ -578,7 +578,7 @@ body:has(#schema-reference) {
     border-radius: 9999px;
 
     border: 6px solid var(--highlight-color);
-    color: white
+    color: white;
 
     font-size: 1.5rem;
     font-weight: 700;