diff --git a/web/markdown/markdown-spoiler.react.js b/web/markdown/markdown-spoiler.react.js
--- a/web/markdown/markdown-spoiler.react.js
+++ b/web/markdown/markdown-spoiler.react.js
@@ -14,7 +14,16 @@
   function MarkdownSpoiler(props: MarkdownSpoilerProps): React.Node {
     const { text } = props;
 
-    return <span className={css.spoiler}>{text}</span>;
+    const onSpoilerClick = (event: SyntheticEvent<HTMLAnchorElement>) => {
+      event.currentTarget.classList.remove(css.spoiler);
+      event.currentTarget.classList.add(css.revealSpoilerAnimation);
+    };
+
+    return (
+      <span className={css.spoiler} onClick={onSpoilerClick}>
+        {text}
+      </span>
+    );
   },
 );
 
diff --git a/web/markdown/markdown.css b/web/markdown/markdown.css
--- a/web/markdown/markdown.css
+++ b/web/markdown/markdown.css
@@ -44,6 +44,19 @@
   color: #33332c;
   cursor: pointer;
 }
+span.revealSpoilerAnimation {
+  animation: revealSpoiler 1s;
+}
+@keyframes revealSpoiler {
+  from {
+    background: #33332c;
+    color: #33332c;
+  }
+  to {
+    background: transparent;
+    color: white;
+  }
+}
 
 div.markdown pre {
   padding: 0.5em 10px;