Allow modal secondary button to shrink and allow wider confirmation modals (#10586)

Fixes #10531

app/javascript/styles/mastodon/components.scss

@@ -3961,14 +3961,6 @@ a.status-card.compact:hover {
   font-size: 14px;
 }
 
-.confirmation-modal {
-  max-width: 85vw;
-
-  @media screen and (min-width: 480px) {
-    max-width: 380px;
-  }
-}
-
 .mute-modal {
   line-height: 24px;
 }
@@ -4147,6 +4139,10 @@ a.status-card.compact:hover {
       color: darken($lighter-text-color, 4%);
     }
   }
+
+  .confirmation-modal__secondary-button {
+    flex-shrink: 1;
+  }
 }
 
 .confirmation-modal__container,