Hi @VKe ,
That's because only subsets of html tags and attributes are supported in alerts:
You can use HTML to format messages in a custom template. The following tags and attributes are allowed in templates:
https://docs.databricks.com/en/sql/user/alerts/index.html
Tags: <a>, <abbr>, <acronym>, <b>, <blockquote>, <body>, <br>, <code>, <div>, <em>, <h1>, <h2>, <h3>, <h4>, <h5>, <h6>, <head>, <hr>, <html>, <i>, <li>, <ol>, <p>, <span>, <strong>, <table>, <tbody>, <td>, <th>, <tr>, <ul>
Attributes: href (for <a>), title (for <a>, <abbr>, <acronym>)