docs: fix styling and content

- Black background instead of blue
- Remove 'dev' from build commands
- Shorter problem descriptions
- Fix missing infrastructure description (DBs, APIs, K8s)

docs/architecture/styles.css

@@ -1,12 +1,12 @@
 :root {
-    --bg-primary: #1a1a2e;
-    --bg-secondary: #16213e;
-    --bg-card: #0f3460;
+    --bg-primary: #0a0a0a;
+    --bg-secondary: #141414;
+    --bg-card: #1a1a1a;
     --text-primary: #eee;
     --text-secondary: #a0a0a0;
     --accent: #e94560;
     --accent-secondary: #533483;
-    --border: #2a2a4a;
+    --border: #2a2a2a;
 }
 
 * {
@@ -16,14 +16,22 @@
 }
 
 body {
-    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
+    font-family:
+        "Segoe UI",
+        system-ui,
+        -apple-system,
+        sans-serif;
     background: var(--bg-primary);
     color: var(--text-primary);
     line-height: 1.6;
 }
 
 header {
-    background: linear-gradient(135deg, var(--bg-secondary), var(--accent-secondary));
+    background: linear-gradient(
+        135deg,
+        var(--bg-secondary),
+        var(--accent-secondary)
+    );
     padding: 2rem;
     text-align: center;
     border-bottom: 2px solid var(--accent);