TOP-1390 remove margin on challenges feed

Author: kkartunov

src/shared/components/Dashboard/Challenges/styles.scss

@@ -128,6 +128,7 @@ $dashboard-dark-bg: #2a2a2a;
 
 .container.light {
   color: $tc-white;
+  margin-bottom: 0;
 
   .header {
     padding: 19px 0;