diff --git a/assets/css/frontend/cms-download.css b/assets/css/frontend/cms-download.css
index e22ca51a..8d1fa39d 100644
--- a/assets/css/frontend/cms-download.css
+++ b/assets/css/frontend/cms-download.css
@@ -203,6 +203,7 @@
 .aksrt-dl-modal.is-cashier .aksrt-dl-modal__body {
   position: relative;
   min-height: 120px;
+  padding-top: 120px;
 }
 
 .aksrt-dl-modal .modal-colorful-header,
@@ -276,7 +277,7 @@
 
 .aksrt-dl-modal .modal-pay-body {
   padding: 15px;
-  margin-top: 120px;
+  margin-top: 0;
 }
 
 .aksrt-cashier__loading {
diff --git a/src/Core/FrontSubmit.php b/src/Core/FrontSubmit.php
index 55b46c06..1f5747ea 100644
--- a/src/Core/FrontSubmit.php
+++ b/src/Core/FrontSubmit.php
@@ -81,30 +81,57 @@ class FrontSubmit {
         return $this->user_can_cap($cap, $user_id);
     }
 
+    public static function upload_limit_bytes(string $kind): int {
+        $settings = class_exists('\AKSRT\Settings\Settings') ? \AKSRT\Settings\Settings::get_all() : [];
+        $configured_mb = match ($kind) {
+            'image'    => max(1, min(20, (int) ($settings['submit_image_max_size'] ?? 5))),
+            'video'    => max(1, min(200, (int) ($settings['submit_video_max_size'] ?? 30))),
+            'resource' => max(1, min(200, (int) ($settings['resource_max_size'] ?? 50))),
+            default    => 0,
+        };
+        if ($configured_mb === 0) {
+            return 0;
+        }
+
+        return min($configured_mb * MB_IN_BYTES, (int) wp_max_upload_size());
+    }
+
     public function rest_upload_attachment(\WP_REST_Request $request) {
         $kind    = (string) $request->get_param('kind');
         $user_id = get_current_user_id();
         $files   = $request->get_file_params();
         $file    = $files['file'] ?? null;
 
-        if (!is_array($file) || empty($file['tmp_name']) || !empty($file['error'])) {
+        if (!is_array($file)) {
             return new \WP_Error('aksrt_upload_missing_file', __('请选择要上传的文件。', 'aksrt'), ['status' => 400]);
         }
 
-        $settings = class_exists('\AKSRT\Settings\Settings') ? \AKSRT\Settings\Settings::get_all() : [];
-        $max_mb = match ($kind) {
-            'resource' => max(1, min(200, (int) ($settings['resource_max_size'] ?? 50))),
-            'video'    => max(1, min(200, (int) ($settings['submit_video_max_size'] ?? 30))),
-            default    => max(1, min(20, (int) ($settings['submit_image_max_size'] ?? 5))),
-        };
-        $max_size = $max_mb * MB_IN_BYTES;
+        $max_size = self::upload_limit_bytes($kind);
+        $upload_error = (int) ($file['error'] ?? UPLOAD_ERR_NO_FILE);
+        if ($upload_error === UPLOAD_ERR_INI_SIZE || $upload_error === UPLOAD_ERR_FORM_SIZE) {
+            return new \WP_Error(
+                'aksrt_upload_too_large',
+                sprintf(__('文件大小不能超过 %s。', 'aksrt'), size_format($max_size)),
+                ['status' => 413]
+            );
+        }
+        if ($upload_error === UPLOAD_ERR_PARTIAL) {
+            return new \WP_Error('aksrt_upload_partial', __('文件未完整上传，请重新选择。', 'aksrt'), ['status' => 400]);
+        }
+        if ($upload_error === UPLOAD_ERR_NO_FILE || empty($file['tmp_name'])) {
+            return new \WP_Error('aksrt_upload_missing_file', __('请选择要上传的文件。', 'aksrt'), ['status' => 400]);
+        }
+        if ($upload_error !== UPLOAD_ERR_OK) {
+            return new \WP_Error('aksrt_upload_failed', __('服务器无法保存上传文件。', 'aksrt'), ['status' => 500]);
+        }
+
         $size     = (int) ($file['size'] ?? 0);
 
         if ($size <= 0 || $size > $max_size) {
             return new \WP_Error(
                 'aksrt_upload_too_large',
-                sprintf(__('文件大小不能超过 %dMB。', 'aksrt'), $max_mb),
-                ['status' => 400]
+                sprintf(__('文件大小不能超过 %s。', 'aksrt'), size_format($max_size)),
+                ['status' => 413]
             );
         }
 
diff --git a/templates/pages/page-submit.php b/templates/pages/page-submit.php
index 51496750..8841778f 100644
--- a/templates/pages/page-submit.php
+++ b/templates/pages/page-submit.php
@@ -79,10 +79,9 @@ if (file_exists($js)) {
 			true
 		);
 	}
-	$attachment_settings = class_exists('\\AKSRT\\Settings\\Settings') ? \AKSRT\Settings\Settings::get_all() : [];
-	$submit_image_max_size = max(1, min(20, (int) ($attachment_settings['submit_image_max_size'] ?? 5))) * MB_IN_BYTES;
-	$submit_video_max_size = max(1, min(200, (int) ($attachment_settings['submit_video_max_size'] ?? 30))) * MB_IN_BYTES;
-	$resource_max_size = max(1, min(200, (int) ($attachment_settings['resource_max_size'] ?? 50))) * MB_IN_BYTES;
+	$submit_image_max_size = \AKSRT\Core\FrontSubmit::upload_limit_bytes('image');
+	$submit_video_max_size = \AKSRT\Core\FrontSubmit::upload_limit_bytes('video');
+	$resource_max_size = \AKSRT\Core\FrontSubmit::upload_limit_bytes('resource');
 
 	wp_localize_script('aksrt-front-submit', 'aksrtSubmitData', [
 		'ajaxUrl'   => admin_url('admin-ajax.php'),
diff --git a/tests/widget-system/front-submit-editor-contract.test.cjs b/tests/widget-system/front-submit-editor-contract.test.cjs
index e1cc488c..ad4ba31d 100644
--- a/tests/widget-system/front-submit-editor-contract.test.cjs
+++ b/tests/widget-system/front-submit-editor-contract.test.cjs
@@ -16,6 +16,22 @@ test('front submit enqueues the WordPress editor before wp_head is rendered', ()
   assert.ok(enqueueAt < headerAt, 'editor assets must be queued before get_header()/wp_head');
 });
 
+test('front submit uploads use the effective WordPress server limit', () => {
+  const controller = read('src/Core/FrontSubmit.php');
+  const page = read('templates/pages/page-submit.php');
+
+  assert.match(controller, /function upload_limit_bytes\(string \$kind\): int/);
+  assert.match(controller, /min\(\$configured_mb \* MB_IN_BYTES, \(int\) wp_max_upload_size\(\)\)/);
+  assert.match(controller, /UPLOAD_ERR_INI_SIZE/);
+  assert.match(controller, /UPLOAD_ERR_FORM_SIZE/);
+  assert.match(controller, /UPLOAD_ERR_PARTIAL/);
+  assert.match(controller, /\['status' => 413\]/);
+  assert.match(page, /FrontSubmit::upload_limit_bytes\('image'\)/);
+  assert.match(page, /FrontSubmit::upload_limit_bytes\('video'\)/);
+  assert.match(page, /FrontSubmit::upload_limit_bytes\('resource'\)/);
+  assert.doesNotMatch(page, /\$attachment_settings\s*=/);
+});
+
 test('published post content reaches the front submit editor unchanged', () => {
   const context = read('templates/parts/submit/context.php');
   const editor = read('templates/parts/submit/editor-main.php');
diff --git a/tests/widget-system/pay-card-contract.test.cjs b/tests/widget-system/pay-card-contract.test.cjs
index c26271ec..3870ec06 100644
--- a/tests/widget-system/pay-card-contract.test.cjs
+++ b/tests/widget-system/pay-card-contract.test.cjs
@@ -100,6 +100,9 @@ test('the article cashier uses the reference modal contract and one direct asset
   assert.match(css, /\.aksrt-dl-modal \.modal-colorful-header/);
   assert.match(css, /\.aksrt-dl-modal \.payment-method-radio/);
   assert.match(css, /\.aksrt-dl-modal \.but\.initiate-pay/);
+  assert.match(css, /\.aksrt-dl-modal\.is-cashier \.aksrt-dl-modal__body\s*\{[^}]*padding-top:\s*120px;/s);
+  assert.match(css, /\.aksrt-dl-modal \.modal-pay-body\s*\{[^}]*margin-top:\s*0;/s);
+  assert.doesNotMatch(css, /\.aksrt-dl-modal \.modal-pay-body\s*\{[^}]*margin-top:\s*120px;/s);
   assert.match(assets, /assets\/css\/frontend\/cms-download\.css/);
   assert.match(assets, /filemtime\(\$cms_download_css_path\)/);