style(course-teaser): add borders inbetween course-teasers

frontend/src/utils/course-teaser/course-teaser.scss

@@ -1,9 +1,12 @@
 [uw-course-teaser] {
+  --course-border-color: var(--color-grey);
+  --course-padding-hori: 10px;
+  --course-padding-vert: 16px;
+
   display: grid;
   grid-gap: 5px 7px;
   grid-template-columns: 50px 120px 1fr;
-  padding: 10px;
-  /* background-color: var(--course-bg-color); */
+  padding: var(--course-padding-vert) var(--course-padding-hori);
   transition: background-color .1s ease-out;
 
   &:not(.course-teaser__disabled) {
@@ -15,10 +18,14 @@
   }
 
   + [uw-course-teaser] {
-    margin-top: 10px;
+    border-top: 1px solid var(--course-border-color);
   }
 }
 
+.course-teaser__disabled {
+  opacity: 0.7;
+}
+
 /* chevron */
 .course-teaser__chevron {
   cursor: pointer;
@@ -161,12 +168,12 @@ course teaser: header styling
     text-align: left;
     border-radius: 20px 20px 20px 20px / 50% 50% 50% 50%;
     margin-right: 30px;
-  
+
     .course-header-link {
       color: white;
       font-weight: bold;
       text-decoration: none;
-  
+
       &:hover {
         color: inherit;
       }