Pages and templates wrap hyperlinks with span tags to make buttons, see URL above and e.g. https://en.wikipedia.org/wiki/Template:Blue_button and https://commons.wikimedia.org/wiki/Template:Clickable_button
This doesn't work with mw-ui-button mw-ui-progressive. The hyperlink styling in skins/common/commonElements.css
a { color: #0645ad; }
and the browser's handling of visited/unvisited hy win out over the surrounding Agora styling.
Perhaps mediawiki.ui.button should apply styles to <a> tags within. Or pages can put spans inside links, so instead of
<span class="mw-ui-button mw-ui-progressive mw-ui-big">[[Download|Get MediaWiki]]</span>
use
[[Download|<span class="mw-ui-button mw-ui-progressive mw-ui-big">Get MediaWiki</span>]]
If the latter works reliably then this bug can be WONTFIX.
In generated HTML we specifying classes directly on the link, i.e. <a href class="mw-ui-...">, but there are bugs with that too, e.g. bug 48184.
Version: unspecified
Severity: normal
URL: https://www.mediawiki.org/wiki/MediaWiki/Homepage_redesign/Preview