Style the download button, and stop it revoking its own download
#download-results was the only button in the tool with no variant rule, so it
fell back to the browser's default button background with the base rule's
transparent border. Next to the bordered GitHub link it read as disabled. It
was never disabled: nothing sets that attribute on it and the click handler
was wired the whole time.
The handler had a real bug behind the cosmetic one. It revoked the object URL
on the same tick as the click and never put the anchor in the document, which
cancels the download in some browsers.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>