>>/31460/
I went on to look into LynxChan's source code to see how sage input is treated. It uses toLowerCase() method of Javascript.
https://gitgud.io/InfinityNow/LynxChan/-/blob/master/src/be/engine/postingOps/post.js
And precisely, latest commit
https://gitgud.io/InfinityNow/LynxChan/-/commit/2d631fc342e93860c4e73662b0782184795565b7
var saged = (parameters.email && parameters.email.toLowerCase() === 'sage');

You can see how it works in browser console [F12]. Declare variable
let email = "sAGE"
Then
console.log(email.toLowerCase())
Should print lowercase
sage
To reassign it use this:
email = "sAge"

To cover all cases we'll then need to specify 2⁴=16 permutations of word sage since CSS does not support regular expressions (yet) :^)

.linkName:is([href="mailto:SAGE"],[href="mailto:SAGe"],[href="mailto:SAgE"],[href="mailto:SAge"],[href="mailto:SaGE"],[href="mailto:SaGe"],[href="mailto:SagE"],[href="mailto:Sage"],[href="mailto:sAGE"],[href="mailto:sAGe"],[href="mailto:sAgE"],[href="mailto:sAge"],[href="mailto:saGE"],[href="mailto:saGe"],[href="mailto:sagE"],[href="mailto:sage"]):after {
  content: "SAGE!";
  float: right;
  color: red;
  padding: 4px;
}


Fun fact: these rules don't work when you access site from cloudflare domains with JS disabled. Kohlchan, which runs on LynxChan fork has no email field at all and uses checkbox for sage, displays it as separate span
SÄGE!

> We used to have something similar on 8chan

Do you have a good snapshot of page with CSS to see how it looked? I checked archive links above and it doesn't look impressive, lots of shit broken. Besides, changing a couple of background colors is not that hard, I don't see a point if it still looks ugly.

I have some ideas in mind, mostly about fixing multiple images, text wrapping around them nicely and post/catalog widths first, borrowing some ideas from cool kids' chans like old Arisu:
https://web.archive.org/web/20210429092636/https://arisuchan.jp/cyb/
Russian neighbors have nice big readable fonts and no "Posting mode: Reply" #modeBanner div on page (something server-side?)
https://endchan.org/dobrochan/

What annoys me most is sticky header: every time you jump to post anchor, it overlaps top row, and I have tried everything, it doesn't fucking work? Like what the fuck. I barely know CSS better than you, few hours of reading tutorials. Here's what I tried:
https://stackoverflow.com/questions/4086107/fixed-page-header-overlaps-in-page-anchors
https://css-tricks.com/hash-tag-links-padding/
https://stackoverflow.com/questions/10732690/offsetting-an-html-anchor-to-adjust-for-fixed-header

Now to my complaints about bold markup. This file has some answers:
https://gitgud.io/InfinityNow/LynxChan/-/blob/master/doc/Markdown.txt
> Observation: it will be run against individual lines of the message, not against the whole message at once.

They should definitely include this on help page.

Now let me test if this thing gobbles up language-specific syntax:
[code css]
#modeBanner {
    display: none;
}