app: drop focus-within styling

This ended up causing dual focus rings which goes against ARIA recommendations.

src/app/app.scss

@@ -23,7 +23,6 @@
 
     &-activities {
         display: flex;
-        @include pb.focus-within();
     }
 
     &-terminal {
@@ -31,7 +30,6 @@
         padding-top: 8px;
         padding-left: 8px;
         background-color: white;
-        @include pb.focus-within();
 
         .#{bp.$ns}-dark & {
             background-color: black;

src/variables.scss

@@ -46,19 +46,3 @@ $pt-dark-outline-color: rgba(bp.$blue5, 0.6);
         outline-offset: $offset;
     }
 }
-
-// add a focus ring when focus is within a container
-@mixin focus-within() {
-    position: relative;
-
-    &:focus-within::after {
-        content: '';
-        pointer-events: none;
-        position: absolute;
-        top: 0;
-        left: 0;
-        width: 100%;
-        height: 100%;
-        @include focus-outline(-3px);
-    }
-}