fix: align Button and Header with design guideline

- Secondary button hover: full espresso fill with white text
- Tertiary button: font-medium (500) and subtle hover background
- Primary button hover: exact 1px translateY
- Header: backdrop-blur 10px (was 4px) and z-index 100 (was 50)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/layout/Header.tsx

@@ -16,7 +16,7 @@ export function Header({ navigation, settings }: HeaderProps) {
   const [isMobileMenuOpen, setIsMobileMenuOpen] = useState(false)
 
   return (
-    <header className="sticky top-0 z-50 bg-ivory/95 backdrop-blur-sm border-b border-warm-gray">
+    <header className="sticky top-0 z-[100] bg-ivory/95 backdrop-blur-[10px] border-b border-warm-gray">
       <div className="container">
         <div className="flex items-center justify-between py-4">
           {/* Logo */}

src/components/ui/Button.tsx

@@ -27,16 +27,16 @@ type ButtonProps = ButtonAsButton | ButtonAsLink
 const variantStyles: Record<ButtonVariant, string> = {
   primary: `
     bg-brass text-soft-white
-    hover:bg-brass-hover hover:-translate-y-0.5 hover:shadow-md
+    hover:bg-brass-hover hover:-translate-y-px hover:shadow-md
     active:translate-y-0
   `,
   secondary: `
     bg-transparent text-espresso border-[1.5px] border-espresso
-    hover:bg-espresso/10 hover:border-espresso
+    hover:bg-espresso hover:text-soft-white
   `,
   tertiary: `
-    bg-transparent text-espresso
+    bg-transparent text-espresso font-medium
-    hover:text-brass
+    hover:bg-espresso/5 hover:text-brass
   `,
 }