bootstrap 4

assets/styles/components/_comments.scss

@@ -1,5 +1,5 @@
 .comment-list {
-  @include list-unstyled;
+  @extend .list-unstyled;
 }
 .comment-list ol {
   list-style: none;

assets/styles/components/_grid.scss

@@ -1,10 +1,18 @@
 // Grid system
 .main {
-  @include make-sm-column($main-sm-columns);
-  .sidebar-primary & {
-    @include make-sm-column($main-sm-columns - $sidebar-sm-columns);
+  @include make-col();
+
+  @include media-breakpoint-up(sm) {
+    @include make-col-span($main-sm-columns);
+    .sidebar-primary & {
+      @include make-col-span($main-sm-columns - $sidebar-sm-columns);
+    }
   }
 }
 .sidebar {
-  @include make-sm-column($sidebar-sm-columns);
+  @include make-col();
+
+  @include media-breakpoint-up(sm) {
+    @include make-col-span($sidebar-sm-columns);
+  }
 }

assets/styles/components/_wp-classes.scss

@@ -10,23 +10,23 @@
 }
 .aligncenter {
   display: block;
-  margin: ($line-height-computed / 2) auto;
+  margin: ($spacer / 2) auto;
   height: auto;
 }
 .alignleft,
 .alignright {
-  margin-bottom: ($line-height-computed / 2);
+  margin-bottom: ($spacer / 2);
   height: auto;
 }
-@media (min-width: $screen-sm-min) {
+@include media-breakpoint-up(sm) {
   // Only float if not on an extra small device
   .alignleft {
     float: left;
-    margin-right: ($line-height-computed / 2);
+    margin-right: ($spacer / 2);
   }
   .alignright {
     float: right;
-    margin-left: ($line-height-computed / 2);
+    margin-left: ($spacer / 2);
   }
 }
 
@@ -35,7 +35,7 @@
   @extend .thumbnail;
 }
 .wp-caption-text {
-  padding: $thumbnail-caption-padding;
+  padding: $thumbnail-padding;
 }
 
 // Text meant only for screen readers