Port back CSS changes made for EE

app/assets/stylesheets/pages/pipelines.scss

 @mixin flat-connector-before($length: 16px) {
+  overflow: visible;
+  position: relative;
+
   &::before {
     content: '';
     position: absolute;
-    top: 48%;
+    top: 24px;
     left: -$length;
     border-top: 1px solid $border-color;
     width: $length;
@@ -13,12 +16,15 @@
 @mixin build-content() {
   display: inline-block;
   padding: $gl-padding-12 $gl-padding;
-  height: 50px;
   width: 100%;
   border: 1px solid $border-color;
-  border-top: 0;
   background-color: $white-light;
 
+  &:not(.linked-pipeline-content) {
+    height: 50px;
+    border-top: 0;
+  }
+
   &:hover {
     background-color: $gray-100;
     color: $gl-text-color;
@@ -485,7 +491,6 @@
 
     &:not(:first-child) {
       .stage-name {
-        overflow: visible;
         @include flat-connector-before;
       }
     }
@@ -603,18 +608,15 @@
       .spinner {
         top: 2px;
       }
-
-      &.play {
-        svg {
-          left: 2px;
-        }
-      }
     }
   }
 
-  .stage-action svg {
-    left: 1px;
-    top: -2px;
+  .stage-action {
+    border: 1px solid $gray-400;
+
+    svg {
+      left: 1px;
+    }
   }
 }