Better handling of long about messages in story viewer selector

stylesheets/_modules.scss

@@ -4710,6 +4710,14 @@ button.module-image__border-overlay:focus {
             justify-content: flex-start;
           }
 
+          &__text {
+            .module-conversation-list__item--contact-or-conversation--is-checkbox
+              & {
+              /* restrict the growth so it doesn't encroach on the checkbox */
+              -webkit-line-clamp: 1;
+            }
+          }
+
           &__text {
             flex-grow: 1;
             flex-shrink: 1;
@@ -4925,6 +4933,12 @@ button.module-image__border-overlay:focus {
             }
           }
         }
+
+        &--container {
+          margin-left: 8px;
+          /* prevent sibling content from pushing this smaller (min-width: the "!important" of width) */
+          min-width: 20px;
+        }
       }
 
       &__spinner__container {