emit resize message in iframes

public/js/iframeResize.js

@@ -0,0 +1,9 @@
+window.addEventListener('load', (event) => {
+    window.parent.postMessage(["resizeIframe",
+    {
+        "url": document.baseURI,
+        "w": document.body.offsetWidth,
+        "h": document.body.offsetHeight
+    }
+    ], "*");
+})

src/views/tweet.nim

@@ -374,5 +374,6 @@ proc renderTweetEmbed*(tweet: Tweet; path: string; prefs: Prefs; cfg: Config; re
     body:
       tdiv(class="tweet-embed"):
         renderTweet(tweet, prefs, path, mainTweet=true)
+      script(src="/js/iframeResize.js", `defer`="")
 
   result = doctype & $node