By default, the line spacing, or line-height CSS attribute, is set to 31 pixels for maximum web readability.
You can adjust the line-height of your text by pasting the following code into Settings > Style > Custom CSS:
.hg-article-body { line-height: 25px; }
Note: Make sure to select the "Articles" Merge Code to target only the Articles with your CSS:
You can increase or decrease the pixels for the desired height, and this will apply to all text in your articles.