diff --git a/app/assets/stylesheets/components/_autocomplete.scss b/app/assets/stylesheets/components/_autocomplete.scss
index 0e651e9588..ae2fb28087 100644
--- a/app/assets/stylesheets/components/_autocomplete.scss
+++ b/app/assets/stylesheets/components/_autocomplete.scss
@@ -63,7 +63,7 @@ $app-focus-colour: $govuk-focus-colour;
   .autocomplete__option:hover {
     padding: 5px 6px;
 
-    &:before {
+    &::before {
       position: relative;
       top: 3px;
       padding-top: 2px;
diff --git a/app/assets/stylesheets/components/_image-cropper.scss b/app/assets/stylesheets/components/_image-cropper.scss
index f8a3f4624f..350d3011cc 100644
--- a/app/assets/stylesheets/components/_image-cropper.scss
+++ b/app/assets/stylesheets/components/_image-cropper.scss
@@ -14,7 +14,7 @@ $app-cropper-point-size: 20px;
 
   .cropper-line,
   .cropper-point,
-  .cropper-point.point-se:before {
+  .cropper-point.point-se::before {
     background-color: $govuk-focus-colour;
   }
 
diff --git a/app/assets/stylesheets/components/_markdown-guidance.scss b/app/assets/stylesheets/components/_markdown-guidance.scss
index 36143ed8b9..d4e0052605 100644
--- a/app/assets/stylesheets/components/_markdown-guidance.scss
+++ b/app/assets/stylesheets/components/_markdown-guidance.scss
@@ -35,7 +35,7 @@
 .app-c-markdown-guidance__item {
   list-style: none;
 
-  &:before {
+  &::before {
     content: "+";
   }
 
diff --git a/app/assets/stylesheets/components/_miller-columns.scss b/app/assets/stylesheets/components/_miller-columns.scss
index 0087387a10..900d23e5d2 100644
--- a/app/assets/stylesheets/components/_miller-columns.scss
+++ b/app/assets/stylesheets/components/_miller-columns.scss
@@ -11,12 +11,12 @@
 
   // Remove box-shadow set in govuk-frontend for govuk-checkboxes__input
   // as we rely on the parent element miller-columns__item to show the target area on hover
-  .govuk-checkboxes__item:hover .govuk-checkboxes__input:focus + .govuk-checkboxes__label:before,
-  .govuk-checkboxes__item:hover .govuk-checkboxes__input:not(:disabled) + .govuk-checkboxes__label:before {
+  .govuk-checkboxes__item:hover .govuk-checkboxes__input:focus + .govuk-checkboxes__label::before,
+  .govuk-checkboxes__item:hover .govuk-checkboxes__input:not(:disabled) + .govuk-checkboxes__label::before {
     box-shadow: none;
   }
 }
 
-.miller-columns__item--parent:after {
+.miller-columns__item--parent::after {
   margin-top: -15px;
 }
diff --git a/app/assets/stylesheets/components/_toolbar-dropdown.scss b/app/assets/stylesheets/components/_toolbar-dropdown.scss
index e0f28b6744..92c6fbe0bd 100644
--- a/app/assets/stylesheets/components/_toolbar-dropdown.scss
+++ b/app/assets/stylesheets/components/_toolbar-dropdown.scss
@@ -44,7 +44,7 @@ $app-dropdown-arrow-spacing: $app-dropdown-arrow-size / 2;
     box-shadow: none;
   }
 
-  &:after {
+  &::after {
     content: "";
     position: relative;
     top: 4px;