For browsers like Firefox 1 etc, I think most of the issues with broken browsers is due to a lack of css support, so gracefully degrading for this kind of scenario shouldn't "in thoery" be too taxing (realties aside). By this I mean that your not supporting an old browser per-se, but a general "standards gap" that is more common to old browsers.
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Although browsers such as Mosaic proved more popular in the earliest days of the web, Lynx has been around since the start with its initial beta release occurring in July 1992 and it remains
(How to) Run Old Versions of Internet Explorer In Windows Nov 02, 2016 25+ Cool Alternative Web Browsers You Didn't Know of - RankRed Jan 01, 2020
Mozilla Firefox is a free, open source, cross-platform, graphical web browser developed by the Mozilla Corporation and hundreds of volunteers. The browser began… Download & More. Flock Browser. Flock was a web browser that specialized in providing social networking and Web 2.0 facilities built into its user interface. Earlier versions of
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