feat(前端界面): 优化滚动条样式，配色更轻盈协调

assets/webui/ofdgo.css

@@ -285,6 +285,13 @@ body[data-hide-meta] .meta-panel {
 	display: none;
 }
 
+.page-list-panel,
+.viewer-panel,
+.meta-panel {
+	scrollbar-width: thin;
+	scrollbar-color: var(--line-strong) transparent;
+}
+
 .page-list-panel,
 .meta-panel {
 	min-height: 0;