Show swipe instruction for the first view

In the post and blog pages
Fixed PanosSakkos/personal-jekyll-theme#75

css/grayscale.scss

@@ -331,3 +331,41 @@ body {
     100% { opacity:1; }
 }
 /* END Added in { Personal } for Typed Cursor in Header */
+
+/* Animation for hand-swipe */
+@-webkit-keyframes swipe {
+    from {
+        left: 5%;
+    }
+    to {
+        left: -5%;
+    }
+}
+
+@-moz-keyframes swipe {
+    from {
+        left: 5%;
+    }
+    to {
+        left: -5%;
+    }
+}
+/* END Animation for hand-swipe */
+
+/* Style for swipe instruction section */
+#swipe-instruction {
+    .modal-content {
+        background-color: rgba(20, 20, 20, 0.6);
+        padding: 10px;
+        @media(min-width:768px) {
+          padding: 100px 0;
+        }
+        #hand-swipe {
+            font-size: 80px;
+            display: block;
+            position: relative;
+            animation: swipe ease-in-out 1s alternate infinite;
+        }
+    }
+}
+/* END Style for swipe instruction section */