feat: implement epub service, navigation service, and global error boundary with updated reader UI layouts

src/NexusReader.UI.Shared/wwwroot/app.css

@@ -27,6 +27,12 @@
 }
 
 
+* {
+    box-sizing: border-box;
+    -webkit-font-smoothing: antialiased;
+    -moz-osx-font-smoothing: grayscale;
+}
+
 body {
     background-color: var(--nexus-bg);
     color: var(--nexus-text);
@@ -44,6 +50,26 @@ body {
     overflow-x: hidden;
 }
 
+/* Modern Scrollbars */
+::-webkit-scrollbar {
+    width: 6px;
+    height: 6px;
+}
+
+::-webkit-scrollbar-track {
+    background: transparent;
+}
+
+::-webkit-scrollbar-thumb {
+    background: rgba(255, 255, 255, 0.1);
+    border-radius: 10px;
+}
+
+::-webkit-scrollbar-thumb:hover {
+    background: rgba(255, 255, 255, 0.2);
+}
+
+
 /* Platform Specific Tweaks */
 .platform-mobile .nexus-button {
     min-height: var(--touch-target-size);