Hide the Drafts warning in the sidebar when no draft's send has failed (#247)

The mark carried `hidden` on the Font Awesome <i>, whose .fa-solid rule
sets display and lands after Tailwind's utilities, so it showed at every
count, on every install, with no draft marked. `hidden` now sits on a
wrapper span with no other display utility (an `inline-flex` beside it
won as well). The test checks for both.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

templates/_partials/_unsent_mark.html.twig

@@ -12,6 +12,12 @@ The sidebar's is rendered at every count and hidden at zero, the idiom every
 patched marker follows (see _new_dot.html.twig): ui--sidebar finds it by
 `data-count-key` after a counts refresh, and an element never rendered cannot
 be found.
+
+`hidden` goes on a wrapper, never on the <i>: Font Awesome's .fa-solid sets
+`display` and lands after Tailwind's utilities, so a `hidden` on the icon is
+overridden and the mark shows at zero — which is how it first shipped, on every
+install, with no draft marked at all. _thread_row.html.twig wraps its icons for
+the same reason.
 #}
 {% macro row(failure) %}
     {% set reason = ('thread_row.send_failed.' ~ failure.value)|trans %}
@@ -23,10 +29,14 @@ be found.
 {% endmacro %}
 
 {% macro sidebar(count) %}
-    <i class="fa-solid fa-triangle-exclamation text-red-600 dark:text-red-400 text-xs{{ count > 0 ? '' : ' hidden' }}"
-       role="img"
-       data-unsent-mark
-       data-count-key="unsent:role:drafts"
-       title="{{ 'sidebar.badge.unsent'|trans }}"
-       aria-label="{{ 'sidebar.badge.unsent'|trans }}"></i>
+    {# No display utility beside `hidden`: one of those would be a second
+       `display` competing with it, and it lost to `inline-flex` here once. #}
+    <span class="text-xs{{ count > 0 ? '' : ' hidden' }}"
+          role="img"
+          data-unsent-mark
+          data-count-key="unsent:role:drafts"
+          title="{{ 'sidebar.badge.unsent'|trans }}"
+          aria-label="{{ 'sidebar.badge.unsent'|trans }}">
+        <i class="fa-solid fa-triangle-exclamation text-red-600 dark:text-red-400" aria-hidden="true"></i>
+    </span>
 {% endmacro %}

tests/Controller/Mail/UnsentDraftWarningTest.php

@@ -58,7 +58,7 @@ final class UnsentDraftWarningTest extends WebTestCase
 
         $mark = $crawler->filter('[data-unsent-mark]')->first();
         self::assertStringNotContainsString('hidden', (string) $mark->attr('class'), 'and Drafts in the sidebar shows it');
-        self::assertStringContainsString('fa-triangle-exclamation', (string) $mark->attr('class'), 'as the same triangle');
+        self::assertCount(1, $mark->filter('i.fa-triangle-exclamation'), 'as the same triangle');
 
         self::assertSame(1, $this->counts($client)['unsent:role:drafts'], 'and the live counts agree');
     }
@@ -72,7 +72,14 @@ final class UnsentDraftWarningTest extends WebTestCase
         self::assertResponseIsSuccessful();
 
         self::assertCount(0, $crawler->filter('[data-unsent-draft]'));
-        self::assertStringContainsString('hidden', (string) $crawler->filter('[data-unsent-mark]')->first()->attr('class'), 'rendered, but hidden at zero');
+
+        $mark = $crawler->filter('[data-unsent-mark]')->first();
+        self::assertStringContainsString('hidden', (string) $mark->attr('class'), 'rendered, but hidden at zero');
+        self::assertStringNotContainsString('fa-', (string) $mark->attr('class'),
+            'and hidden by an element Font Awesome does not style: its .fa-solid sets display after '
+            . 'Tailwind, so `hidden` on the icon itself does not hide it');
+        self::assertDoesNotMatchRegularExpression('/(^|\s)(inline-flex|inline-block|flex|block|inline|grid)(\s|$)/', (string) $mark->attr('class'),
+            'and with no other display utility competing with `hidden`');
         self::assertSame(0, $this->counts($client)['unsent:role:drafts']);
     }