Clean up templates and CSS

- season.html.twig: remove dead empty column, drop redundant flex-row
- tab_overview.html.twig: extract Twig macro for confirm modals, fix duplicate aria-labelledby IDs
- tab_result.html.twig: remove dead comment, replace inline widths with CSS classes, simplify nested row/col forms to d-flex gap-1
- backoffice.scss: add col-result-xs/sm/md column width classes
- quiz.scss: replace broken display:grid + justify-self:center with flexbox centering

templates/backoffice/season.html.twig

@@ -14,7 +14,7 @@
     <h2 class="mb-3">{{ 'Season'|trans }}: {{ season.name }}</h2>
     <div class="row">
         <div class="col-md-6 col-12">
-            <div class="d-flex flex-row align-items-center mb-3">
+            <div class="d-flex align-items-center mb-3">
                 <h4 class="mb-0 pe-2">{{ 'Quizzes'|trans }}</h4>
                 <a class="link"
                    href="{{ path('tvdt_backoffice_quiz_add', {seasonCode: season.seasonCode}) }}">{{ 'Add'|trans }}</a>
@@ -29,7 +29,7 @@
             </div>
         </div>
         <div class="col-md-3 col-12">
-            <div class="d-flex flex-row align-items-center mb-3">
+            <div class="d-flex align-items-center mb-3">
                 <h4 class="mb-0 pe-2">{{ 'Candidates'|trans }}</h4>
                 <a class="link"
                    href="{{ path('tvdt_backoffice_add_candidates', {seasonCode: season.seasonCode}) }}">{{ 'Add Candidate'|trans }}
@@ -40,11 +40,10 @@
                     <li>{{ candidate.name }}</li>{% endfor %}
             </ul>
 
-            <div class="d-flex flex-row align-items-center mb-3">
+            <div class="d-flex align-items-center mb-3">
                 <h4 class="mb-0 pe-2">{{ 'Settings'|trans }}</h4>
             </div>
             {{ form(form) }}
         </div>
-        <div class="col-12 col-md-3"></div>
     </div>
 {% endblock body %}