Strange behavior when clicking the page on Android phone

The pages of Rust course(e.g., Rust by example) may contain a bug. Sometimes, clicking the page on Android phone causes the page return to the top, so I need swipe the screen to skip the contents I have read.

Where exactly are you clicking? It seems to be working ok for me.

[ Also, what browser are you using? I wonder if it might be a browser bug ]

Firefox Focus.