feat(前端界面): 优化确认框布局与按钮对齐

assets/webui/index.html

@@ -186,10 +186,10 @@
 				<button id="batchPagesButton" class="editor-group-action" type="button">页面</button>
 			</div>
 		</div>
-		<dialog id="closePanel" class="form-dialog">
+		<dialog id="closePanel" class="form-dialog confirm-dialog">
 			<form method="dialog">
 				<h2 class="form-title">关闭文档</h2>
-				<div class="form-row">文档尚未保存</div>
+				<p class="confirm-message">文档尚未保存</p>
 				<div class="form-actions"><button class="button" value="cancel" autofocus>取消</button><button class="button" value="discard">放弃</button><button class="button" value="save">保存</button></div>
 			</form>
 		</dialog>