fix: Make hero title and stat numbers white for dark background

Replace gradient-clip text on .hero-title and .stat-number with plain
white (#ffffff) so they are clearly visible against the dark hero
background. Bump CSS cache to v4.

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

Author: danribes

css/style.css

@@ -397,10 +397,7 @@ ul {
 .hero-title {
     font-size: 4.5rem;
     margin-bottom: 0.5rem;
-    background: var(--gradient-primary);
-    -webkit-background-clip: text;
-    -webkit-text-fill-color: transparent;
-    background-clip: text;
+    color: #ffffff;
     animation: slideInFromTop 0.8s ease-out;
     text-shadow: 0 0 40px rgba(102, 126, 234, 0.3);
 }
@@ -452,10 +449,7 @@ ul {
 .stat-number {
     font-size: 3rem;
     font-weight: 700;
-    background: var(--gradient-primary);
-    -webkit-background-clip: text;
-    -webkit-text-fill-color: transparent;
-    background-clip: text;
+    color: #ffffff;
     margin-bottom: 0.5rem;
     display: block;
 }

index.html

@@ -7,7 +7,7 @@
     <meta name="keywords" content="health economist, HEOR, HTA, market access, economic modeling, health technology assessment">
     <meta name="author" content="Daniel Ribes">
     <title>Daniel Ribes - Senior Health Economist | HEOR & Market Access Expert</title>
-    <link rel="stylesheet" href="css/style.css?v=3">
+    <link rel="stylesheet" href="css/style.css?v=4">
     <link rel="preconnect" href="https://fonts.googleapis.com">
     <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
     <link href="https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Poppins:wght@600;700&display=swap" rel="stylesheet">