diff --git a/.env b/.env
new file mode 100644
index 0000000..c789158
--- /dev/null
+++ b/.env
@@ -0,0 +1,2 @@
+VITE_API_BASE=http://backend:8000
+VITE_WIZARD_PORT=8080
diff --git a/Dockerfile b/Dockerfile
index 90fcc6f..75ff17e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -3,13 +3,6 @@ FROM node:20-alpine AS build
 WORKDIR /app
 COPY package.json package-lock.json* ./
 RUN npm install
-
-# Set build args and env vars BEFORE copying source code
-ARG VITE_WIZARD_PORT=18080
-ARG VITE_API_BASE
-ENV VITE_WIZARD_PORT=$VITE_WIZARD_PORT
-ENV VITE_API_BASE=$VITE_API_BASE
-
 COPY . .
 RUN npm run build
 
diff --git a/src/pages/SetupWizardPage.tsx b/src/pages/SetupWizardPage.tsx
index 46b85bc..3e9bc47 100644
--- a/src/pages/SetupWizardPage.tsx
+++ b/src/pages/SetupWizardPage.tsx
@@ -38,7 +38,7 @@ export default function SetupWizardPage({ wizardBase, onComplete }: Props) {
     db_user: 'harborforge',
     db_password: 'harborforge_pass',
     db_database: 'harborforge',
-    backend_base_url: 'http://127.0.0.1:8000',
+    backend_base_url: 'http://backend:8000',
     project_name: '',
     project_description: '',
   })
@@ -182,7 +182,7 @@ export default function SetupWizardPage({ wizardBase, onComplete }: Props) {
             <h2>Backend URL</h2>
             <p className="text-dim">Configure the HarborForge backend API URL</p>
             <div className="setup-form">
-              <label>Backend Base URL <input value={form.backend_base_url} onChange={(e) => set('backend_base_url', e.target.value)} placeholder="http://127.0.0.1:8000" /></label>
+              <label>Backend Base URL <input value={form.backend_base_url} onChange={(e) => set('backend_base_url', e.target.value)} placeholder="http://backend:8000" /></label>
             </div>
             <div className="setup-nav">
               <button className="btn-back" onClick={() => setStep(2)}>Back</button>