Fix styles of "Show all" link button on ReactionsRow (#8658)

Author: luixxiul

res/css/views/messages/_ReactionsRow.scss

@@ -57,15 +57,16 @@ limitations under the License.
 }
 
 .mx_ReactionsRow_showAll {
-    @mixin ButtonResetDefault;
-    text-decoration: none;
-    font-size: $font-12px;
-    line-height: $font-20px;
-    margin-left: 4px;
-    vertical-align: middle;
     color: $tertiary-content;
 
-    &:hover {
-        color: $primary-content;
+    &.mx_AccessibleButton_kind_link_inline {
+        font-size: $font-12px;
+        line-height: $font-20px;
+        margin-inline-start: $spacing-4;
+        vertical-align: middle;
+
+        &:hover {
+            color: $primary-content;
+        }
     }
 }