Basically, if you are ok with it only taking affect after page load (so users see first the original page then the new version) it is trivial. However flash of wrongly styled content is a really bad user experience.<div><br></div><div>To do it without the flash of wrong version of toggle, is difficult due to the way our infrastructure is currently setup. Nothing insurmountable in principle, but high effort and involves some tradeoffs that seems not worth it in context.</div><div><br></div><div>--</div><div>Brian</div><div><br></div><div>p.s. for the avoidance of doubt, this is my personal opinion and not an &quot;official&quot; answer in any capacity.</div><div><div><br>On Friday, September 30, 2022, Samuel Klein &lt;<a href="mailto:meta.sj@gmail.com">meta.sj@gmail.com</a>&gt; wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Dear WT,<div><br></div><div>The perennial discussion about ways to provide logged-out users with persistent customization of their reading experience in the browser has cropped up again in the context of the pending deployment of Vector 2022.</div><div><br></div><div>Can a <a href="https://en.wikipedia.org/wiki/Wikipedia:Requests_for_comment/Deployment_of_Vector_(2022)#Alt_proposal:_gradual_changeover_+_width_toggle" target="_blank">cookie-based width toggle</a> be offered without splitting the cache or otherwise making the toggler regret their tog?</div><div><br></div><div>The answers currently range from &quot;<span style="color:rgb(32,33,34);font-family:sans-serif"><i>shouldn&#39;t be very complicated or hacky, just toggling a class</i>...&quot; and &quot;</span><span style="color:rgb(32,33,34);font-family:sans-serif"><i>can be delivered to logged-out users on top of the cached parser output</i>..&quot;  to &quot;<i>impossible</i>&quot;.</span></div><div><br></div><div>Could someone clarify the challenges and costs of trying to toggle css classes in this way?</div><div><br></div><div>Warmly, SJ</div><div><div><br></div>-- <br><div dir="ltr" data-smartmail="gmail_signature">Samuel Klein          @metasj           w:user:sj          +1 617 529 4266<br></div></div></div>
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