Add execution result.

redesign/nimforum.scss

@@ -290,3 +290,15 @@ blockquote {
     margin-bottom: $control-padding-y;
   }
 }
+
+.execution-result {
+  @extend .toast;
+
+  h6 {
+    font-family: $base-font-family;
+  }
+}
+
+.execution-success {
+  @extend .toast-success;
+}

redesign/thread.html

@@ -140,7 +140,7 @@
               <pre class="code" data-lang="Nim"><code>proc hello(x: int) =
   echo("Hello ", x)
 
-42.hello()</code><div class="code-buttons"><button class="btn btn-primary btn-sm">Run</button></div></pre>
+42.hello()</code><div class="code-buttons"><button class="btn btn-primary btn-sm">Run</button></div></pre><pre class="execution-result execution-success"><button class="btn btn-clear float-right"></button><h6>Output</h6>Hello 42</pre>
 
 <p>The greatest function ever written is <code>hello</code>.</p>
 <blockquote>