Added a thin blue line using a separate header-line.css file

Maintained the existing header gradient and all other functionality
No modifications to existing variables or hover effects

public/components/header.html

@@ -20,6 +20,7 @@
             <i class="fas fa-bars"></i>
         </button>
     </div>
+    <div class="header-horizontal-line"></div>
     <script>
         // Hide expertise and contact links on non-index pages
         if (window.location.pathname !== '/' && window.location.pathname !== '/index.html') {

public/css/header-line.css

@@ -0,0 +1,8 @@
+.header-horizontal-line {
+    position: absolute;
+    bottom: 0;
+    left: 0;
+    width: 100%;
+    height: 1px;
+    background-color: var(--primary);
+}

public/css/header.css

@@ -2,7 +2,7 @@ header {
     position: fixed;
     top: 0;
     width: 100%;
-    background: linear-gradient(350deg, var(--header-gradient-1), var(--header-gradient-2));
+    background: linear-gradient(90deg, var(--header-gradient-1), var(--header-gradient-2));
     backdrop-filter: blur(10px);
     padding: var(--spacing-lg) var(--spacing-md);
     z-index: 1000;

public/css/variables.css

@@ -10,9 +10,10 @@
     --bg-card: #f5f5f5;
     --text: #333333;
     --text-muted: #666666;
-    --header-gradient-1: rgba(245, 245, 245, 0.9);
+    --header-gradient-1: rgba(220, 220, 220, 0.9);
     --header-gradient-2: rgba(235, 235, 235, 0.9);
     --border-color: rgba(58, 123, 224, 0.1);
+    --bg-hover-rgb: 207, 207, 207;
 }
 
 [data-theme="dark"] {
@@ -22,6 +23,7 @@
     --text-muted: #888888;
     --header-gradient-1: rgba(14, 14, 14, 0.9);
     --header-gradient-2: rgba(41, 41, 41, 0.9);
+    --bg-hover-rgb: 17, 17, 17;
 }
 
 /* Common tokens */

public/index.html

@@ -16,6 +16,7 @@
     <link rel="stylesheet" href="css/components.css">
     <link rel="stylesheet" href="css/footer.css">
     <link rel="stylesheet" href="css/header.css">
+    <link rel="stylesheet" href="css/header-line.css">
     <link rel="stylesheet" href="css/layout.css">
     <link rel="stylesheet" href="css/responsive.css">
     <link rel="stylesheet" href="css/variables.css">