fix(preflight): exclude iframes from :-moz-focusring outline

Prevent Firefox from applying auto outline to iframes when :focus-visible
is triggered. This fixes an issue where iframes would show an unwanted
outline when focused.

Fixes #19795

Author: cyphercodes

integrations/cli/index.test.ts

@@ -2392,7 +2392,7 @@ test(
           border-color: inherit;
           border-collapse: collapse;
         }
-        :-moz-focusring {
+        :-moz-focusring:where(:not(iframe)) {
           outline: auto;
         }
         progress {

packages/tailwindcss/preflight.css

@@ -170,7 +170,7 @@ table {
   Use the modern Firefox focus style for all focusable elements.
 */
 
-:-moz-focusring {
+:-moz-focusring:where(:not(iframe)) {
   outline: auto;
 }