about:blank domain exception for background color


I've set the following to have about:blank be displayed in blue :
@-moz-document url("about:blank") {html {background:#004CD0;}}

I omitted the !important so up to now I've encountered no color problem on sites using about:blank
Yet, I encounter a true difficulty on protonmail.com which uses about:blank in its email composition window ... resulting in the background color I've chosen.

I'd like to know if it's possible to insert in the above rule an exception for a given domain :
@-moz-document url("about:blank") {html {background:#004CD0;}} BUT NOT on domain1, domain2



  • edited October 8 Firefox
    If there is a way to detect that about:blank is in an iframe (and not style it there), that should solve the problem. But I'm not aware of such a thing in pure CSS. (User scripts can distinguish, but usually do not run on about: pages.)

    What if you think about it the other way around: a common way a site enables about:blank as a rich text editor composition area is to add the contenteditable attribute to an element, perhaps the body. So maybe something like --
    @-moz-document url("about:blank") {
    html {background:#004CD0;}
    body[contenteditable] {background:#f5f5f5;}
    -- would work?
  • myfmyf
    edited October 9 Chrome

    I'm using head:empty + body:empty selector to prevent unwanted styling of about:blank content when something alters its content for quite a while and it seems to work well in Firefox with Stylish.

    OP, you your UA reads Chrome, my Stylus tells me it is not possible to style about:blank in Chrome. Even if it was, my approach would not most probably work, if style was injected into document like it is from userscript.

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