fix: add light/dark mode support with Tailwind dark: prefix

src/components/sections/contact-section.tsx

@@ -103,9 +103,9 @@ export function ContactSection() {
   }
 
   return (
-    <section id="contact" className="section-padding relative" ref={sectionRef}>
+    <section id="contact" className="section-padding relative bg-gray-50 dark:bg-[var(--color-bg-secondary)]" ref={sectionRef}>
       <div className="absolute inset-0 pointer-events-none">
-        <div className="absolute bottom-0 left-0 w-96 h-96 bg-gradient-radial from-[#C41E3A]/3 to-transparent rounded-full blur-3xl -translate-x-1/2 translate-y-1/2" />
+        <div className="absolute bottom-0 left-0 w-96 h-96 bg-gradient-radial from-[var(--color-tech-blue)]/3 to-transparent rounded-full blur-3xl -translate-x-1/2 translate-y-1/2" />
       </div>
 
       <div className="container-wide relative z-10">
@@ -116,13 +116,13 @@ export function ContactSection() {
           `}
         >
           <div className="flex items-center gap-3 mb-4">
-            <div className="w-8 h-px bg-[#C41E3A]" />
-            <span className="text-sm text-[#525252] tracking-wide">联系我们</span>
+            <div className="w-8 h-px bg-gradient-to-r from-[var(--color-tech-blue)] to-[var(--color-tech-purple)]" />
+            <span className="text-sm text-gray-600 dark:text-gray-400 tracking-wide">联系我们</span>
           </div>
-          <h2 className="text-3xl sm:text-4xl font-semibold text-[#171717] tracking-tight chapter-title">
+          <h2 className="text-3xl sm:text-4xl font-semibold text-gray-900 dark:text-white tracking-tight chapter-title">
             开启合作
           </h2>
-          <p className="mt-4 text-[#737373] max-w-2xl">
+          <p className="mt-4 text-gray-600 dark:text-gray-400 max-w-2xl">
             无论您有任何问题或合作意向，我们都很乐意与您交流
           </p>
         </div>