Duolingo app is using a sans-serif (gothic) font for showing hiragana now. It feels clean and modern, but it may not be the best choice for a beginner.

Instead, if it's using a serif (mincho) font, it would also show how a hiragana is written.

Here is a visual comparison between sans-serif (gothic) and serif (mincho):

As you can see, serif (mincho) can show how a character is written, also known as the order of strokes (笔顺 in Chinese), which is very important in CJK writing systems.

Disclaimer: I'm a native speaker of Chinese, a long time Duolingo user, recently I'm picking up Japanese in Duolingo.