feat: overlay title and metadata on hero images

- Position title and metadata absolutely over hero images
- Add gradient background for text readability (dark at bottom)
- Use backdrop-filter blur for metadata badges
- White text with shadow for better contrast
- Maintain original layout when no image present
- Creates more immersive reading experience

src/components/ReaderHeader.tsx

@@ -17,13 +17,35 @@ const ReaderHeader: React.FC<ReaderHeaderProps> = ({
   hasHighlights,
   highlightCount
 }) => {
+  if (image) {
+    return (
+      <div className="reader-hero-image">
+        <img src={image} alt={title || 'Article image'} />
+        {title && (
+          <div className="reader-header-overlay">
+            <h2 className="reader-title">{title}</h2>
+            <div className="reader-meta">
+              {readingTimeText && (
+                <div className="reading-time">
+                  <FontAwesomeIcon icon={faClock} />
+                  <span>{readingTimeText}</span>
+                </div>
+              )}
+              {hasHighlights && (
+                <div className="highlight-indicator">
+                  <FontAwesomeIcon icon={faHighlighter} />
+                  <span>{highlightCount} highlight{highlightCount !== 1 ? 's' : ''}</span>
+                </div>
+              )}
+            </div>
+          </div>
+        )}
+      </div>
+    )
+  }
+
   return (
     <>
-      {image && (
-        <div className="reader-hero-image">
-          <img src={image} alt={title || 'Article image'} />
-        </div>
-      )}
       {title && (
         <div className="reader-header">
           <h2 className="reader-title">{title}</h2>

src/index.css

@@ -1071,6 +1071,8 @@ body {
   margin: 0 0 2rem 0;
   border-radius: 8px;
   overflow: hidden;
+  position: relative;
+  min-height: 300px;
 }
 
 .reader-hero-image img {
@@ -1081,6 +1083,41 @@ body {
   display: block;
 }
 
+.reader-header-overlay {
+  position: absolute;
+  bottom: 0;
+  left: 0;
+  right: 0;
+  padding: 2rem 2rem 1.5rem;
+  background: linear-gradient(to top, rgba(0, 0, 0, 0.85) 0%, rgba(0, 0, 0, 0.6) 60%, rgba(0, 0, 0, 0) 100%);
+}
+
+.reader-header-overlay .reader-title {
+  color: #fff;
+  text-shadow: 0 2px 8px rgba(0, 0, 0, 0.5);
+  margin-bottom: 0.75rem;
+}
+
+.reader-header-overlay .reader-meta {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+  flex-wrap: wrap;
+}
+
+.reader-header-overlay .reading-time,
+.reader-header-overlay .highlight-indicator {
+  background: rgba(255, 255, 255, 0.15);
+  backdrop-filter: blur(8px);
+  border: 1px solid rgba(255, 255, 255, 0.25);
+  color: #fff;
+}
+
+.reader-header-overlay .highlight-indicator {
+  background: rgba(100, 108, 255, 0.25);
+  border: 1px solid rgba(100, 108, 255, 0.4);
+}
+
 /* Private Bookmark Styles */
 .private-bookmark {
   background: #2a2a2a;