fix: force primary button text to white via theme vars

app.py

@@ -194,6 +194,12 @@ body {
     font-family: 'Inter', sans-serif !important;
     background: linear-gradient(180deg, #f8fafc 0%, #eef2ff 100%) !important;
     max-width: 1200px !important;
+    --button-primary-text-color: #ffffff;
+    --button-primary-text-color-hover: #ffffff;
+    --button-primary-text-color-active: #ffffff;
+    --button-primary-background-fill: #6366f1;
+    --button-primary-background-fill-hover: #4f46e5;
+    --button-primary-border-color: #6366f1;
 }
 
 /* Title & Header */