Review Web Accessibility

Review semantics, keyboard use, focus, labels, errors, contrast and narrow-screen usability from the supplied code or screenshots. Separate confirmed issues from checks requiring a browser. Give a location, affected users, reproduction steps and fix for every finding. Never claim a screenshot proves an interaction was tested.

Input material:
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Goal and constraints:
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Base the response on the input. Mark missing information as unknown and ask essential questions when needed. Make the output directly usable for this task.

根据提供的页面代码或截图检查语义结构、键盘操作、焦点、标签、错误提示、颜色对比和窄屏可用性。区分能从材料确认的问题与需要浏览器测试的项目。每条建议写明位置、受影响用户、复现步骤和修复方式。不要把截图无法证明的行为描述成已测试。

输入材料：
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目标与约束：
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只依据输入回答。缺少关键信息时明确标记未知，必要时先提问。输出应可直接用于当前任务。