If you leave it even for just a little while, you forget how to do it
If I leave it even for just a little while, I forget how to draw properly.
If I leave it even for just a little while, I forget the words I learnt.
「少しでも間が空くと〜出来なくなる」= If you leave it even for just a little while, you forget how to do it
「少しでも間が空くと、上手く描けなくなる」= If I leave it even for just a little while, I forget how to draw properly.
「少しでも間が空くと、覚えた単語の意味を忘れてしまう」= If I leave it even for just a little while, I forget the words I learnt.
ボキャブラリー
if I leave it = 時間を空ける
even just for = 少しでも
forget how to = ~のやり方を忘れる・出来なくなる