Timestamps may be specified in several formats, see the Timestamp library input formats documented on mediawiki.org for details. ISO 8601 date and time is recommended: 2001-01-15T14:56:00Z. Additionally, the string now may be used to specify the current timestamp.
You shouldn't even be seeing this. Bizzeebeever told me to add this here so that we can get responsiveness working for all screens.