style: 给上传日志「暂无预览」添加了样式。

admin/src/pages/config/upload.vue

@@ -176,8 +176,9 @@ const image_arr = ['png', 'jpeg', 'jpg', 'gif']
                     </template>
                   </el-image>
                 </div>
+                <div class="no_preview_wrapper" v-else>暂无预览</div>
               </div>
-              <div v-else>暂无预览</div>
+              <div class="no_preview_wrapper" v-else>暂无预览</div>
             </template>
           </el-table-column>
           <el-table-column label="UUID" prop="uuid"></el-table-column>
@@ -199,6 +200,12 @@ const image_arr = ['png', 'jpeg', 'jpg', 'gif']
   </div>
 </template>
 <style scoped>
+.no_preview_wrapper {
+  line-height: 100px;
+  text-align: center;
+  color: #999999;
+}
+
 .table_image_wrapper {
   width: 200px;
   aspect-ratio: 1/1;