tweaking loading animation so that it removes more smoothly

lms/static/sass/_discussion.scss

@@ -1290,6 +1290,9 @@ body.discussion {
       }
 
       &.loading {
+        height: 0;
+        margin: 0;
+        padding: 0;
         border: none;
         box-shadow: none;
       }
@@ -1596,6 +1599,7 @@ body.discussion {
         padding: 10px 10px 40px;
 
         .discussion-post {
+          padding: 17px 23px;
           @include clearfix;
 
           header {

lms/static/sass/base/_base.scss

@@ -137,9 +137,11 @@ span.edx {
 }
 
 .loading-animation {
+  position: absolute;
+  left: 50%;
   width: 20px;
   height: 20px;
-  margin: auto;
+  margin-left: -10px;
   background: url(../images/spinner.gif) no-repeat;
 }