CCM-12126: Fix frontend styles (#696)

Author: nicki-nhs

frontend/src/components/molecules/AuthLink/AuthLink.module.scss

@@ -1,8 +1,3 @@
 .auth-link {
-  color: var(--color_nhsuk-white);
   padding: 1em;
-
-  &:visited {
-    color: var(--color_nhsuk-white);
-  }
 }

frontend/src/components/molecules/PreviewTemplateDetails/PreviewTemplateDetails.module.scss

@@ -1,5 +1,6 @@
 .preview {
-  background-color: var(--color_nhsuk-white);
+  background-color: var(--nhsuk-card-background-colour);
+  border: solid 1px var(--nhsuk-border-colour);
 
   & :global(.nhsuk-summary-list__key) {
     width: 20%;

frontend/src/styles/_nhs-variables.scss

@@ -8,7 +8,7 @@ body {
 code {
   display: inline-block;
   padding: 0.6rem;
-  background-color: var(--nhsuk-border-color);
+  background-color: nhsuk.$nhsuk-template-background-colour;
 }
 
 pre {
@@ -21,8 +21,8 @@ pre {
 }
 
 .notify-confirmation-panel {
-  color: var(--color_nhsuk-white);
-  background-color: var(--color_nhsuk-green);
+  color: nhsuk.$nhsuk-reverse-text-colour;
+  background-color: nhsuk.$nhsuk-success-colour;
   text-align: center;
   padding: 1.5rem;
   margin-bottom: 2.5rem;