a word of warning: if you have carefully created your own "looks" of DateLine, changing to the "minimalist" theme will make you lose it - there's no way to go back, other than to the default theme. Your own one will be gone without warning. I had to get mine back from the latest TimeMachine backup, it's in file ~/Library/Preferences/com.machinecodex.dateline.plist in your User folder.
So, to keep your own theme, before switching themes for the first time, save your own one by adding a new theme (plus button on the lower left in the preferences-appearance), giving it a name (e.g. "My Theme").
The software should certainly do that for you automatically...
ah, and while we're at that: please, dev, bring back the option to display the month above the dateline as it was in early versions of the program.