Fix spacing for very small screens

index.html

@@ -137,12 +137,13 @@
         display: -webkit-box;
         display: -ms-flexbox;
         display: flex;
+        gap: 1em;
         margin: 2em -.5em;
         -ms-flex-wrap: wrap;
             flex-wrap: wrap;
       }
       .main-grid > * {
-        margin: .5em;
+        box-sizing: border-box;
         -ms-flex-preferred-size: 20em;
             flex-basis: 20em;
         -webkit-box-flex: 1;