Unsupported browsers – please stick to industry standards (HTML5, CSS3, …) not vendor‑specific extension

Please remove this stupid

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banner. It wastes valuable screen space. What’s next? Optimized for 3840 px × 2160 px?

Also now I have to deal with three scrollbars: One for the lesson navigation, one for the article/video/Q&A content, and another one to scroll past that dumb banner.