Best practices for self-closing tags. <br /> or <br>

With UXP, what is the best practice for self-closing tags, like

<br> or <br />
<meta> or <meta />

and several others

Include the space and forward slash or not?

I ran some website code through an HTML validator and received a message that the space and forward slash are no longer necessary. Wondering if this is true in UXP as well.

IIRC in HTML world it’s recommended by W3C not to use the forward slash with the break tag (cite needed). I have ran into some odd errors by including the forward slash. IIRC UXP is based on a browser engine with unnecessaries stripped away. IMO Go without the forward slash and if you have issues post here.

Just noticed the Kitchen Sink plugin uses:

<br />