fix:修改样式

src/App.tsx

@@ -223,10 +223,12 @@ function App() {
   }, [autoPlay, isStageMode])
 
   const progress = ((activeIndex + 1) / sections.length) * 100
+  const techSectionIndex = sections.findIndex((s) => s.id === 'tech')
+  const isTechTopbar = !isStageMode && techSectionIndex >= 0 && activeIndex >= techSectionIndex
 
   return (
     <div className={isStageMode ? 'site is-stage' : 'site'}>
-      <header className="topbar">
+      <header className={isTechTopbar ? 'topbar is-tech-theme' : 'topbar'}>
         <a className="brand-lockup" href="#hero" onClick={() => goToSection(0)}>
           <img className="haoke-logo-img" src="/assets/haoke-logo.png" alt="杜康好客" />
           <span>