Multiple UI improvements (#4671)

PLT-4638 - Removing close buttons from modals

Updating UI for filter and search on mobile

Reverting utils

webapp/sass/responsive/_mobile.scss

@@ -85,8 +85,13 @@
     }
 
     .app__body {
-        .edit-modal-body {
+        .more-modal {
+            .filter-row {
+                width: 330px;
+            }
+        }
 
+        .edit-modal-body {
             .custom-textarea {
                 max-height: 30vh;
             }
@@ -160,16 +165,6 @@
         }
     }
 
-    .member-select__container {
-        margin-bottom: 10px;
-        margin-top: 10px;
-        overflow: hidden;
-        position: relative;
-        right: 10px;
-        top: 0;
-        width: 100%;
-    }
-
     .user-popover {
         pointer-events: none;
     }
@@ -1334,6 +1329,34 @@
     }
 }
 
+@media screen and (max-width: 550px) {
+    .app__body {
+        .more-modal {
+            &.more-direct-channels {
+                .filter-row {
+                    padding-bottom: 50px;
+                    width: 100%;
+                }
+
+                .member-show {
+                    display: none;
+                }
+
+                select {
+                    margin: 0;
+                    width: 100%;
+                }
+            }
+        }
+    }
+
+    .member-select__container {
+        left: 15px;
+        top: 60px;
+        width: calc(100% - 30px);
+    }
+}
+
 @media screen and (max-width: 480px) {
     .sidebar--right {
         .post {