diff --git a/src/components/branding/SecuirdLogo.tsx b/src/components/branding/SecuirdLogo.tsx
index aa80334..a77c51c 100644
--- a/src/components/branding/SecuirdLogo.tsx
+++ b/src/components/branding/SecuirdLogo.tsx
@@ -7,9 +7,8 @@ interface SecuirdLogoProps {
 }
 
 /**
- * Secuird Logo - Abstract gate/doorway mark
- * Represents controlled entry and policy enforcement
- * Two vertical pillars forming a gateway with negative space
+ * Secuird Logo — Abstract gate/doorway mark
+ * Uses CSS variables so the color automatically adapts to the active theme.
  */
 export function SecuirdLogo({ 
   size = "md", 
@@ -22,6 +21,8 @@ export function SecuirdLogo({
     lg: "w-12 h-12",
   };
 
+  // Tailwind classes resolve to hsl(var(--primary)) / hsl(var(--sidebar-primary))
+  // which pick up the injected --theme-primary / --theme-sidebar-primary values.
   const bgClasses = {
     default: "bg-primary",
     light: "bg-sidebar-primary",
@@ -48,28 +49,10 @@ export function SecuirdLogo({
           size === "sm" ? "w-4 h-4" : size === "md" ? "w-5 h-5" : "w-6 h-6"
         )}
       >
-        {/* Abstract gate - two pillars with archway */}
-        <path 
-          d="M4 4h3v16H4V4z" 
-          fill="currentColor"
-        />
-        <path 
-          d="M17 4h3v16h-3V4z" 
-          fill="currentColor"
-        />
-        <path 
-          d="M7 4h10v3H7V4z" 
-          fill="currentColor"
-          opacity="0.7"
-        />
-        {/* Keyhole/entry indicator */}
-        <circle 
-          cx="12" 
-          cy="14" 
-          r="2" 
-          fill="currentColor"
-          opacity="0.5"
-        />
+        <path d="M4 4h3v16H4V4z" fill="currentColor" />
+        <path d="M17 4h3v16h-3V4z" fill="currentColor" />
+        <path d="M7 4h10v3H7V4z" fill="currentColor" opacity="0.7" />
+        <circle cx="12" cy="14" r="2" fill="currentColor" opacity="0.5" />
       </svg>
     </div>
   );
diff --git a/src/components/branding/ThemeIndicator.tsx b/src/components/branding/ThemeIndicator.tsx
new file mode 100644
index 0000000..8ab13a1
--- /dev/null
+++ b/src/components/branding/ThemeIndicator.tsx
@@ -0,0 +1,31 @@
+import { config } from "@/config";
+
+interface ThemeIndicatorProps {
+  showBanner?: boolean;
+  className?: string;
+}
+
+/**
+ * Visual theme indicator — solid-colored banner for dev/preprod environments.
+ */
+export function ThemeIndicator({ showBanner = true }: ThemeIndicatorProps) {
+  const theme = config.theme.name;
+  const appName = config.app.name;
+
+  if (theme === "default") return null;
+
+  const labels: Record<string, string> = {
+    dev: "Development Environment",
+    preprod: "Staging / Pre-Production",
+  };
+
+  if (showBanner) {
+    return <div className="env-banner">{labels[theme] || theme} — {appName}</div>;
+  }
+
+  return (
+    <span className="inline-flex items-center px-2.5 py-0.5 rounded-full text-xs font-medium bg-primary/15 text-primary">
+      {labels[theme] || theme}
+    </span>
+  );
+}
diff --git a/src/components/layouts/AuthenticatedLayout.tsx b/src/components/layouts/AuthenticatedLayout.tsx
index 73ab8d6..b192e7e 100644
--- a/src/components/layouts/AuthenticatedLayout.tsx
+++ b/src/components/layouts/AuthenticatedLayout.tsx
@@ -3,11 +3,13 @@ import { SidebarProvider } from "@/components/ui/sidebar";
 import { AppSidebar } from "@/components/navigation/AppSidebar";
 import { TopBar } from "@/components/navigation/TopBar";
 import ApiDevTools from "@/components/dev/ApiDevTools";
+import { ThemeIndicator } from "@/components/branding/ThemeIndicator";
 
 export default function AuthenticatedLayout() {
   return (
     <SidebarProvider>
-      <div className="min-h-screen flex w-full bg-background">
+      <ThemeIndicator />
+      <div className="min-h-screen flex w-full bg-background pt-8">
         <AppSidebar />
         <div className="flex-1 flex flex-col min-w-0">
           <TopBar />
diff --git a/src/components/layouts/MarketingLayout.tsx b/src/components/layouts/MarketingLayout.tsx
index e5998f2..d957dbc 100644
--- a/src/components/layouts/MarketingLayout.tsx
+++ b/src/components/layouts/MarketingLayout.tsx
@@ -1,16 +1,17 @@
 import { Link, Outlet, useLocation } from "react-router-dom";
 import { SecuirdLogo as GatehouseLogo } from "@/components/branding/SecuirdLogo";
+import { ThemeIndicator } from "@/components/branding/ThemeIndicator";
 import { Button } from "@/components/ui/button";
 import { config } from "@/config";
 import { cn } from "@/lib/utils";
 import {
-Shield,
-Key,
-CreditCard,
-Play,
-Lock,
-Menu,
-X
+  Shield,
+  Key,
+  CreditCard,
+  Play,
+  Lock,
+  Menu,
+  X
 } from "lucide-react";
 import { useState } from "react";
 
@@ -29,8 +30,11 @@ const [mobileMenuOpen, setMobileMenuOpen] = useState(false);
 
 return (
 <div className="min-h-screen bg-background flex flex-col">
+  {/* Theme indicator banner for dev/staging */}
+  <ThemeIndicator />
+  
   {/* Header */}
-  <header className="sticky top-0 z-50 w-full border-b bg-background/95 backdrop-blur supports-[backdrop-filter]:bg-background/60">
+  <header className="sticky top-8 z-50 w-full border-b bg-background/95 backdrop-blur supports-[backdrop-filter]:bg-background/60 marketing-header">
     <nav className="mx-auto max-w-7xl px-4 sm:px-6 lg:px-8">
       <div className="flex h-16 items-center justify-between">
         {/* Logo */}
diff --git a/src/components/layouts/PublicLayout.tsx b/src/components/layouts/PublicLayout.tsx
index 2966d3c..b77cc33 100644
--- a/src/components/layouts/PublicLayout.tsx
+++ b/src/components/layouts/PublicLayout.tsx
@@ -1,15 +1,19 @@
 import { Outlet, Link } from "react-router-dom";
 import { SecuirdLogo } from "@/components/branding/SecuirdLogo";
+import { ThemeIndicator } from "@/components/branding/ThemeIndicator";
 import { config } from "@/config";
 
 export default function PublicLayout() {
   return (
     <div className="min-h-screen bg-background flex flex-col">
+      {/* Theme indicator banner for dev/staging */}
+      <ThemeIndicator />
+      
       {/* Subtle gradient background */}
       <div className="fixed inset-0 bg-gradient-to-br from-background via-background to-secondary/30 pointer-events-none" />
       
-      {/* Header */}
-      <header className="relative z-10 w-full py-6 px-4">
+      {/* Header with theme-colored border */}
+      <header className="relative z-10 w-full py-6 px-4 marketing-header">
         <div className="max-w-md mx-auto">
           <Link to="/" className="flex items-center gap-2.5 justify-center">
             <SecuirdLogo size="md" />
diff --git a/src/index.css b/src/index.css
index adc4663..7404a0d 100644
--- a/src/index.css
+++ b/src/index.css
@@ -1,7 +1,5 @@
 @import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');
 
-@import './styles/theme-vars.css';
-
 @tailwind base;
 @tailwind components;
 @tailwind utilities;
@@ -14,16 +12,16 @@
 @layer base {
   :root {
     /* Core palette - Light blue-gray with teal accent */
-    --background: 216 22% 94%;        /* cool blue-gray — cards lift clearly off this */
-    --foreground: 222 47% 9%;         /* near-black navy */
+    --background: 216 22% 94%;
+    --foreground: 222 47% 9%;
 
-    --card: 0 0% 100%;                /* pure white — 6% lightness gap over bg */
+    --card: 0 0% 100%;
     --card-foreground: 222 47% 9%;
 
     --popover: 0 0% 100%;
     --popover-foreground: 222 47% 9%;
 
-    /* Primary — theme-configurable (teal default, red for dev, purple for staging) */
+    /* Primary — theme-configurable */
     --primary: var(--theme-primary);
     --primary-foreground: var(--theme-primary-foreground);
 
@@ -31,7 +29,7 @@
     --secondary: 216 20% 91%;
     --secondary-foreground: 222 47% 18%;
 
-    /* Muted — noticeably darker than secondary, used for section bg */
+    /* Muted */
     --muted: 216 18% 88%;
     --muted-foreground: 222 18% 42%;
 
@@ -53,7 +51,7 @@
     --info-foreground: 0 0% 100%;
 
     /* UI chrome */
-    --border: 216 18% 84%;            /* clearly visible on white card */
+    --border: 216 18% 84%;
     --input: 216 18% 92%;
     --ring: var(--theme-ring);
 
@@ -70,12 +68,7 @@
     --sidebar-ring: var(--theme-ring);
     --sidebar-muted: 222 20% 48%;
 
-    /* Gradients */
-    --gradient-brand: linear-gradient(135deg, hsl(var(--theme-primary)), hsl(var(--theme-primary) / 0.8));
-    --gradient-accent: linear-gradient(135deg, hsl(var(--theme-primary)), hsl(var(--theme-primary) / 0.8));
-    --gradient-subtle: linear-gradient(135deg, hsl(216 28% 97%), hsl(216 18% 93%));
-
-    /* Shadows — stronger alpha so cards lift off the bg */
+    /* Shadows */
     --shadow-sm: 0 1px 2px 0 hsl(222 47% 9% / 0.10);
     --shadow-md: 0 4px 6px -1px hsl(222 47% 9% / 0.14), 0 2px 4px -2px hsl(222 47% 9% / 0.10);
     --shadow-lg: 0 10px 15px -3px hsl(222 47% 9% / 0.14), 0 4px 6px -4px hsl(222 47% 9% / 0.10);
@@ -153,6 +146,34 @@
 }
 
 @layer components {
+  /* Environment banner — solid theme color */
+  .env-banner {
+    @apply fixed top-0 left-0 right-0 z-[100] px-3 py-1.5 text-center text-xs font-bold uppercase tracking-wider;
+    background-color: hsl(var(--theme-primary));
+    color: hsl(var(--theme-primary-foreground));
+    box-shadow: 0 2px 4px 0 hsl(var(--theme-primary) / 0.3);
+  }
+
+  /* Sidebar header — solid theme color background */
+  .sidebar-header-themed {
+    background-color: hsl(var(--theme-sidebar-primary));
+    color: hsl(var(--theme-sidebar-primary-foreground));
+    border-bottom: 1px solid hsl(var(--theme-sidebar-primary) / 0.3);
+  }
+
+  /* Top bar — theme-colored bottom border + subtle tint */
+  .top-bar-themed {
+    border-bottom: 2px solid hsl(var(--theme-primary));
+    background-color: hsl(var(--theme-primary) / 0.04);
+  }
+
+  /* Active nav item — theme color background */
+  .active-nav-themed {
+    background-color: hsl(var(--theme-primary) / 0.12);
+    color: hsl(var(--theme-primary));
+    border-radius: var(--radius);
+  }
+
   /* Auth card for public pages */
   .auth-card {
     @apply bg-card rounded-xl p-8 shadow-card border border-border;
@@ -207,7 +228,6 @@
 }
 
 @layer utilities {
-  /* Animation utilities */
   .animate-fade-in {
     animation: fadeIn 0.3s ease-out;
   }
@@ -217,22 +237,12 @@
   }
 
   @keyframes fadeIn {
-    from {
-      opacity: 0;
-    }
-    to {
-      opacity: 1;
-    }
+    from { opacity: 0; }
+    to { opacity: 1; }
   }
 
   @keyframes slideIn {
-    from {
-      opacity: 0;
-      transform: translateY(-8px);
-    }
-    to {
-      opacity: 1;
-      transform: translateY(0);
-    }
+    from { opacity: 0; transform: translateY(-8px); }
+    to { opacity: 1; transform: translateY(0); }
   }
 }
diff --git a/vite.config.ts b/vite.config.ts
index 5fee80e..f5c40e5 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -17,9 +17,21 @@ export default defineConfig(({ mode }) => {
   const appName = env.VITE_APP_NAME || (themeName === "dev" ? "Secuird Dev" : themeName === "preprod" ? "Secuird Staging" : "Secuird");
   const favicon = env.VITE_FAVICON || (themeName === "dev" ? "/favicon-dev.svg" : themeName === "preprod" ? "/favicon-staging.svg" : "/favicon.svg");
 
-  const themeColor = `hsl(${colors.primary})`;
+  const themeColorHsl = `hsl(${colors.primary})`;
+
+  // Build a CSS block that injects directly into <head> before any stylesheets load.
+  const themeStyles = `
+<style data-theme="${themeName}">
+  :root {
+    --theme-primary: ${colors.primary};
+    --theme-primary-foreground: 0 0% 100%;
+    --theme-sidebar-primary: ${colors.sidebarPrimary};
+    --theme-sidebar-primary-foreground: 0 0% 100%;
+    --theme-ring: ${colors.ring};
+    --theme-color: ${themeColorHsl};
+  }
+</style>`;
 
-  
   return {
     server: {
       host: "::",
@@ -37,30 +49,18 @@ export default defineConfig(({ mode }) => {
         transformIndexHtml: {
           order: "pre",
           handler: (html) => {
-            return html
+            const headClose = html.indexOf("</head>");
+            const withStyle = headClose > -1
+              ? html.slice(0, headClose) + themeStyles + "\n" + html.slice(headClose)
+              : html;
+            return withStyle
               .replace(/%VITE_APP_NAME%/g, appName)
               .replace(/%VITE_FAVICON%/g, favicon)
-              .replace(/%VITE_THEME_COLOR%/g, themeColor);
+              .replace(/%VITE_THEME_COLOR%/g, themeColorHsl);
           },
         },
       },
     ],
-    css: {
-      preprocessorOptions: {
-        css: {
-          additionalData: `
-            :root {
-              --theme-primary: ${colors.primary};
-              --theme-primary-foreground: 0 0% 100%;
-              --theme-sidebar-primary: ${colors.sidebarPrimary};
-              --theme-sidebar-primary-foreground: 0 0% 100%;
-              --theme-ring: ${colors.ring};
-              --theme-color: hsl(${colors.primary});
-            }
-          `,
-        },
-      },
-    },
     resolve: {
       alias: {
         "@": path.resolve(__dirname, "./src"),