improve ui

lib/pages/illust_page.dart

@@ -101,7 +101,10 @@ class _IllustGalleryPageState extends State<IllustGalleryPage> {
       length++;
     }
 
-    return PageView.builder(
+    return Stack(
+      children: [
+        Positioned.fill(
+          child: PageView.builder(
             controller: controller,
             itemCount: length,
             itemBuilder: (context, index) {
@@ -111,6 +114,36 @@ class _IllustGalleryPageState extends State<IllustGalleryPage> {
               return IllustPage(illusts[index],
                   nextPage: nextPage, previousPage: previousPage);
             },
+            onPageChanged: (value) => setState(() {}),
+          ),
+        ),
+        if (controller.page! < length - 1 && length > 1)
+          Positioned(
+            right: 16,
+            top: 0,
+            bottom: 0,
+            child: Center(
+                child: IconButton(
+              icon: const Icon(FluentIcons.chevron_right),
+              onPressed: () {
+                nextPage();
+              },
+            )),
+          ),
+        if (controller.page != 0 && length > 1)
+          Positioned(
+            left: 16,
+            top: 0,
+            bottom: 0,
+            child: Center(
+                child: IconButton(
+              icon: const Icon(FluentIcons.chevron_left),
+              onPressed: () {
+                previousPage();
+              },
+            )),
+          ),
+      ],
     );
   }
 
@@ -1014,7 +1047,7 @@ class _BottomBarState extends State<_BottomBar> with TickerProviderStateMixin {
 
   Widget buildMoreActions() {
     return Wrap(
-      runSpacing: 4,
+      runSpacing: 8,
       spacing: 8,
       children: [
         Button(