refactor(article): add default padding (#166)

* refactor(article): add default padding

closes https://github.com/CaiJimmy/hugo-theme-stack/issues/165

* fix(article): video iframe margin

* fix: remove youtube iframe border

layouts/shortcodes/tencent.html

@@ -1,10 +1,10 @@
 {{ $vid := .Get 0 }}
-<div style="position: relative; width: 100%; height: 0; padding-bottom: 56.25%;">
+<div class="video-wrapper">
     <iframe src="http://v.qq.com/txp/iframe/player.html?vid={{ $vid }}&auto=0" 
             scrolling="no" 
             frameborder="no"
             framespacing="0" 
-            allowfullscreen="true" 
-            style="position: absolute; width: 100%; height: 100%;">
+            allowfullscreen="true"
+    >
     </iframe>
 </div>