Multiple UI Improvements (#4069)

Minor contast fix for file uploading text.

Updating icon markup

Fixing icon for mentions

Removing irrelevant characters

Updating closing tag for mentions icon

webapp/sass/layout/_headers.scss

@@ -217,6 +217,12 @@
 .sidebar--left,
 .sidebar--menu,
 .admin-sidebar {
+
+    .divider {
+        border-top: 1px solid transparent;
+        margin: 0.5em 0;
+    }
+
     .team__header {
         @include legacy-pie-clearfix;
         padding: 9px 10px;

webapp/sass/layout/_post-right.scss

@@ -87,7 +87,7 @@
         }
 
         .post-right-comments-upload-in-progress {
-            color: #a8adb7;
+            @include opacity(.7);
             margin-right: 10px;
             padding: 6px 0;
         }

webapp/sass/responsive/_mobile.scss

@@ -5,6 +5,8 @@
         .tutorial__content {
             .tutorial__steps {
                 margin-bottom: 0;
+                min-height: auto;
+                padding-bottom: 8em;
             }
         }
     }

webapp/sass/routes/_signup.scss

@@ -484,13 +484,20 @@
         width: 90%;
     }
 
-    .signup-team-dir__arrow {
+    .signup-team__icon {
         color: $dark-gray;
         float: right;
         font-size: 1.5em;
         line-height: 25px;
         position: relative;
         top: .66em;
+
+        &.fa-spin {
+            color: $gray;
+            font-size: .9em;
+            right: 10px;
+            top: 16px;
+        }
     }
 }