Add mobile media query

style.css

@@ -610,6 +610,16 @@ input[type="range"] {
     .draw-half-upload {
         padding-left: 0;
     }
+
+  .instr-grid {
+    grid-template-columns: repeat(3, 1fr) !important;
+  }
+}
+
+@media (max-width: 480px) {
+  .instr-grid {
+      grid-template-columns: repeat(2, 1fr) !important;
+  }
 }
 
 /* Tab-pill labels that sit ABOVE each card heading, classifying who the