fix challenge layout (#11620)

* wrap challenge task icons + margins

* full width challenge card on small devices + padding under add-challenge button

website/client/src/components/challenges/findChallenges.vue

@@ -68,6 +68,17 @@
 <style lang='scss' scoped>
   @import '~@/assets/scss/colors.scss';
 
+  @media only screen and (max-width: 768px) {
+    .header-row {
+      margin-bottom: 1rem;
+    }
+
+    .col-10.standard-page {
+      // full width on smaller devices
+      max-width: 100%;
+    }
+  }
+
   .header-row {
     h1 {
       color: $purple-200;