How do I apply theme changes?

[bvy]

Hi folks. How do I apply theme changes? I went in and updated some colors to my current theme. But stupidly, there's no Save or Apply button. If I click the X, my changes disappear. 

Is there a hidden Easter egg somewhere? How does this work? Thanks. 

[bvy · Accepted solution]

Know issue. I started tabbing through the fields and they popped up at the bottom.,