add github corner

src/styles/index.scss

@@ -228,3 +228,32 @@ code {
   position: relative;
   margin: 0 auto;
 }
+
+//github-corner
+.github-corner:hover .octo-arm {
+  animation: octocat-wave 560ms ease-in-out
+}
+
+@keyframes octocat-wave {
+  0%,
+  100% {
+    transform: rotate(0)
+  }
+  20%,
+  60% {
+    transform: rotate(-25deg)
+  }
+  40%,
+  80% {
+    transform: rotate(10deg)
+  }
+}
+
+@media (max-width:500px) {
+  .github-corner:hover .octo-arm {
+    animation: none
+  }
+  .github-corner .octo-arm {
+    animation: octocat-wave 560ms ease-in-out
+  }
+}