Updated styling of milestone lists

app/assets/stylesheets/framework/common.scss

@@ -262,10 +262,6 @@ li.note {
 }
 
 .milestone {
-  &.milestone-closed {
-    background: $gray-light;
-  }
-
   .progress {
     margin-top: 4px;
     box-shadow: none;

app/assets/stylesheets/pages/milestone.scss

@@ -3,17 +3,18 @@
 }
 
 .milestones {
-  padding: $gl-padding-top;
+  padding: $gl-padding-8;
   border-radius: $border-radius-default;
-  background-color: $gray-normal;
+  background-color: $theme-gray-100;
 
   .milestone {
+    border: 0;
     padding: $gl-padding-top $gl-padding;
     border-radius: $border-radius-default;
     background-color: $white-light;
 
     &:not(:last-child) {
-      margin-bottom: $gl-padding-8;
+      margin-bottom: $gl-padding-4;
     }
 
     h4 {