Change 571410 had a related patch set uploaded (by VolkerE; owner: VolkerE):
[mediawiki/core@master] Apply normal, cross-browser button appearance on revision history

https://gerrit.wikimedia.org/r/571410

I'd say the same thing applies to the rest of the button elements in the history page. These designs are not consistent at all. In fact, button elements with no additional styling actually are displayed with no border on the mobile site.

	Screenshot of https://www.mediawiki.org/w/index.php?title=MediaWiki&action=history
	Screenshot of https://m.mediawiki.org/w/index.php?title=MediaWiki&action=history

The above screenshots were captured using the same browser, on the same device but on different sites.
The treatment of button elements are very different on the mobile site as you can see. Adding mw-ui-button class is one way to resolve this. But naked button elements without this class should not look different in the same browser in my opinion.

Workaround

As a user, for now I am manually adding this class via a JS hack. Adding mw-ui-button class using jQuery to button elements.

@Jdlrobson thoughts?

Change 571410 merged by jenkins-bot:
[mediawiki/core@master] Apply normal, cross-browser button appearance on revision history

https://gerrit.wikimedia.org/r/571410

Change 571536 had a related patch set uploaded (by VolkerE; owner: VolkerE):
[mediawiki/core@master] Apply normal, cross-browser button appearance on revision history

https://gerrit.wikimedia.org/r/571536

@Masumrezarock100 Indeed, I think this was overlooked because the other buttons don't appear for normal users (only sysops or something). The second commit fixes that.

Change 571536 merged by jenkins-bot:
[mediawiki/core@master] Apply normal, cross-browser button appearance on revision history (part 2)

https://gerrit.wikimedia.org/r/571536