Issue 3490368: Added comment form and styled it.

css/components/form_input.css

@@ -23,3 +23,7 @@ input:valid, input:focus-visible {
   transition: background-color 0.6s ease;
   background-color: hsl(var(--hue), var(--sat), calc(var(--lum) * 0.5));
 }
+form.comment-comment-form input:valid,
+form.comment-comment-form select {
+  border: 1px solid var(--ck-color-base-border);
+}