Fix double margin in "reposition expand thread" feature

Two |.header| elements existed, and so both had right padding set to
16px. This change fixes this and sets the padding to 19px, which is what
the Community Console uses.

Fixed: twpowertools:16
Change-Id: I54ad5e3795b2d7481a0f5b69751c63880a31a085
diff --git a/src/static/css/reposition_expand_thread.css b/src/static/css/reposition_expand_thread.css
index 8df9d2f..f36d1aa 100644
--- a/src/static/css/reposition_expand_thread.css
+++ b/src/static/css/reposition_expand_thread.css
@@ -1,14 +1,14 @@
-ec-thread-summary .panel .main-header {
+ec-thread-summary .panel > .main-header {
   flex-direction: row-reverse;
 }
 
-ec-thread-summary .panel .main-header .expand-container {
+ec-thread-summary .panel > .main-header .expand-container {
   padding: 0 0 0 8px;
 }
 
-ec-thread-summary .panel .main-header .header {
+ec-thread-summary .panel > .main-header > .header {
   padding-left: 0px!important;
-  padding-right: 16px!important;
+  padding-right: 19px!important;
 }
 
 ec-thread-list ec-bulk-actions .selection {