docs: styles on mobile devices

docs/index.html

@@ -51,6 +51,7 @@
             <a @click="share('twitter')"><i class="nes-icon twitter"></i></a>
             <a @click="share('facebook')"><i class="nes-icon facebook"></i></a>
             <a @click="share('linkedin')"><i class="nes-icon linkedin"></i></a>
+            <a @click="share('github')"><i class="nes-icon github"></i></a>
           </div>
         </div>
       </header>

docs/script.js

@@ -579,6 +579,8 @@ new Vue({
             return 'http://www.facebook.com/sharer.php?u=https://nostalgic-css.github.io/NES.css/&t=NES.css%EF%BD%9CNES-style%20CSS%20Framework';
           case 'linkedin':
             return 'https://www.linkedin.com/shareArticle?url=https%3A//nostalgic-css.github.io/NES.css/&title=NES.css%EF%BD%9CNES-style%20CSS%20Framework';
+          case 'github':
+            return 'https://github.com/nostalgic-css/NES.css';
         }
       })();
 

docs/style.css

@@ -211,3 +211,18 @@ h3.topic-title > i {
 .article-link > .title span {
   margin-left: 1rem;
 }
+
+@media screen and (max-width: 768px) {
+  body {
+    margin: 2rem 0.5rem;
+    padding: 0;
+  }
+
+  .github-link {
+    display: none;
+  }
+
+  .message-list > .message > .nes-balloon {
+    max-width: 60%;
+  }
+}