Fix output section to have white background matching Z-Image

- Remove dark inner background from output section divs
- Keep output section white in both light and dark modes
- Match Z-Image styling exactly

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app.py

@@ -395,7 +395,7 @@ div.output-section {
     -webkit-backface-visibility: hidden !important;
 }
 
-/* Inner image area with dark background */
+/* Inner image area - white background matching Z-Image */
 .output-section > div {
     width: 100% !important;
     min-height: 75vh !important;
@@ -403,8 +403,6 @@ div.output-section {
     display: flex !important;
     align-items: center !important;
     justify-content: center !important;
-    background: #1d1d1f !important;
-    border-radius: 12px !important;
 }
 
 .output-section > div > div {
@@ -414,16 +412,14 @@ div.output-section {
     display: flex !important;
     align-items: center !important;
     justify-content: center !important;
-    background: #1d1d1f !important;
-    border-radius: 12px !important;
 }
 
 .output-section * {
     max-width: 100% !important;
 }
 
-/* Dark mode for output section */
-.dark .output-section {
+/* Dark mode - input section only (output stays white like Z-Image) */
+.dark .input-section {
     background: #1d1d1f !important;
     box-shadow: 0 2px 12px rgba(0, 0, 0, 0.4) !important;
 }