Sorry, I have all square corners.

I should have put my userchrome in the original posting ... here it is:

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

.titlebar-color{ color: AccentColorText; background-color: AccentColor; }

.tab-background{ border-radius: 0px !important; margin-bottom: 0px !important; }

.tabbrowser-tab:not([selected=true]):not([multiselected=true]) .tab-background{ background-color: color-mix(in srgb, currentColor 5%, transparent); }

menupopup > menu, menupopup > menuitem{ padding-block: 2px !important; min-height: 0px !important; }

root {

--arrowpanel-border-radius: 0px !important; --arrowpanel-menuitem-border-radius: 0px !important; --arrowpanel-menuitem-padding: 2px !important; --toolbarbutton-border-radius: 0px !important; --tab-border-radius: 0px !important; }

.menupopup-arrowscrollbox{ border-radius: 0px !important; }

In 111, I see these two style rules that use the --toolbarbutton-border-radius variable and disabling both of them gives me square corners.

• chrome://browser/skin/urlbar-searchbar.css
• https://searchfox.org/mozilla-release/source/browser/themes/shared/urlbar-searchbar.css

You would have to override those border-radius rules to 0px via userChrome.css. Do not forget the !important flag to override exiting rules.

• border-radius: 0px !important;

#urlbar-background,
#searchbar {
  background-color: var(--toolbar-field-background-color);
  background-clip: border-box;
  border: 1px solid var(--toolbar-field-border-color);
  /*! border-radius: var(--toolbarbutton-border-radius); */
}

#urlbar-input-container,
#searchbar {
  /*! border-radius: var(--toolbarbutton-border-radius); */
  overflow: clip;
}