So the code is more readable (no horizontal scrolling), you can separate the selectors onto their own lines:

/* set the initial borders of the urlbar and search bar to gray */
#urlbar > #urlbar-background, 
#urlbar[breakout][breakout-extend] > #urlbar-background, 
#searchbar { 
    border: 1px solid #a1a6b5 !important; 
    outline: none !important; 
    border-radius: 0px !important; 
}
/* set urlbar border to blue when focused */
#urlbar[breakout][breakout-extend] #urlbar-background {
    border-color: #0078d7 !important;
}

It's possible that [breakout-extend] refers to the drop-down being open. Are you using the Browser Toolbox to inspect the address bar as you interact with it? https://firefox-source-docs.mozilla.org/devtools-user/browser_toolbox/index.html

When I click inside the address bar to focus it, the toolbox gets deactivated, so I can't see the name of the active element.

Probably the active element is id="urlbar". What's critical is to observe the attributes and class name(s) of the element. Can you tile the browser window to one side of the screen and the Browser Toolbox to the other side to make it easier to observe?

See also:

• https://support.mozilla.org/en-US/questions/1446677#answer-1652543

Hi cor-el,

Yes I saw that post. Even if it's an outline I'm not sure how to code what I want to achieve.

Hi cor-el,

Yes I saw that post. Even if it's an outline I'm not sure how to code what I want to achieve.

Hi jscher2000,

Even with tiling them if I click anywhere the toolbox becomes deactivated. The little blue arrow button in the toolbox turns black.

The closest I can come is the screen capture below (it shows urlbar-container).

The section with the gray border/outline and the shadow may be urlbar-input-container as shown in the below screenshot.

When I compare screenshots with the drop-down open and closed, the most noticeable difference is when it is open, there is this extra attribute:

suppress-focus-border

When you press Esc, that is removed. This is why cor-el's previous discovery was relevant -- it's the rule for when that attribute is missing. https://searchfox.org/mozilla-release/source/browser/themes/shared/urlbar-searchbar.css#86

#urlbar[focused="true"]:not([suppress-focus-border]) > #urlbar-background,
#searchbar:focus-within {
  outline: var(--focus-outline);
  outline-offset: var(--focus-outline-inset);
  /* We used --focus-outline above to inherit its width and style properties,
     but we still want to use the theme's border-color.
     --toolbar-field-focus-border-color is set equal to --focus-outline-color
     on :root, but LWT themes can override this value. */
  outline-color: var(--toolbar-field-focus-border-color);
  border-color: transparent;
}

So if you copy the exact rule and then turn off outline, that should work:

#urlbar[focused="true"]:not([suppress-focus-border]) > #urlbar-background,
#searchbar:focus-within {
  outline: none !important;
}

Edit: added screenshots

Same result with that line. When pressing Esc, the border/outline turns back to gray and the box-shadow remains.

See the animation below from FF 88. I click in the URL bar, the outline turns blue. I type something and then press Escape. The URL bar shrinks, and the blue border remains, with no shadow around it. I click off the URL bar so it loses focus, and only then does its border/outline turn back to gray. That's what I'm trying to replicate.

In FF 88, I think this line look away the shadow when the urlbar was not expanded, but it's not working in FF 115 ESR.

#urlbar[breakout][breakout-extend]:not([open]) > #urlbar-background {
   box-shadow: none !important;
}

Sorry, I forgot you were on 115. I'm on 125 now.

I'm testing on multiple machines, so I keep switching between 115 and 125.