Unfortunately it isnt just css.
In 2.1.0-b3 the dev team have added to the List class config - itemMap this has a config object that sets the minimumHeight to 47px.
Works well with your examples as thats the item height your expecting.
Doesnt work so well when you want a row height that is less like mine which is 35px.
Not sure why 47px was chosen as 44px is apples standard which the violate often
I got around this by adding to the constructor in the list.js
//Override item map minimum height - set by sencha to 47px
me.getItemMap()._minimumHeight = 25;
me.getItemMap().config.minimumHeight = 25;