improvement: all confirmed suggestions implemented

frontend/src/styles/globals.css

@@ -6,10 +6,10 @@
   --radius-md: 6px;
   --radius-lg: 8px;
 
-  --color-background-primary: #f6f9fc;
-  --color-background-secondary: #ffffff;
-  --color-background-card: #ffffff;
-  --color-surface-elevated: #f8fbff;
+  --color-background-primary: #f2f3f5;
+  --color-background-secondary: #f7f8f9;
+  --color-background-card: #f7f8f9;
+  --color-surface-elevated: #eceef1;
 
   --color-text-primary: #0f172a;
   --color-text-secondary: #475569;
@@ -18,7 +18,7 @@
   --color-border: #d2dcec;
   --color-border-strong: #aec0de;
 
-  --color-card-background: #ffffff;
+  --color-card-background: #f7f8f9;
   --color-card-foreground: #0f172a;
   --color-card-muted: #475569;
   --color-card-border: #d2dcec;
@@ -397,7 +397,7 @@ select option {
 @keyframes picker-expand {
   from {
     opacity: 0;
-    transform: scaleX(0.88);
+    transform: translateY(4px) scale(0.98);
   }
   to {
     opacity: 1;
@@ -406,7 +406,7 @@ select option {
 }
 
 .picker-expand {
-  transform-origin: inline-start;
+  transform-origin: top center;
   animation: picker-expand 180ms ease-out;
 }