Stop extending stage column, remove column ids.

app/assets/javascripts/pipelines/components/graph/linked_pipelines_column.vue

@@ -20,7 +20,7 @@ export default {
     linkedPipeline,
   },
   computed: {
-    columnId() {
+    columnClass() {
       return `graph-position-${this.graphPosition}`;
     },
   },
@@ -29,8 +29,8 @@ export default {
 
 <template>
   <div
-    class="linked-pipelines-column"
-    :id="columnId"
+    class="stage-column linked-pipelines-column"
+    :class="columnClass"
     >
     <div class="stage-name linked-pipelines-column-title"> {{ columnTitle }} </div>
     <div class="cross-project-triangle"></div>

app/assets/stylesheets/pages/pipelines.scss

@@ -1003,16 +1003,13 @@
 }
 
 .linked-pipelines-column {
-  @extend .stage-column;
-
   position: relative;
 
   & > ul {
     padding: 0;
   }
 
-  // IDs used to override specificity in stage-column
-  &#graph-position-left {
+  &.graph-position-left {
     margin-right: $linked-project-column-margin;
 
     .cross-project-triangle {
@@ -1020,7 +1017,7 @@
     }
   }
 
-  &#graph-position-right {
+  &.graph-position-right {
     margin-left: $linked-project-column-margin;
 
     .cross-project-triangle {