Viewer: Fix overflow and top part margins

src/style/pages/_viewer.scss

@@ -4,10 +4,10 @@
     height: 100vh;
     min-height: 560px;
     padding-top: 16px;
+    overflow-x: hidden;
 
     @include breakpoint (sm) {
         width: 100%;
-        height: 100vh;
         display: flex;
         flex-direction: column;
         justify-content: space-between;
@@ -28,9 +28,9 @@
         flex-flow: row wrap;
 
         @include breakpoint (sm) {
-            // position: static;
             justify-content: center;
-            margin-bottom: 24px;
+            margin-top: 24px;
+            margin-bottom: 48px;
         }
 
         // Tip message