Accessibility

You can move with a keyboard. Focus is visible, and a sticky bar will not hide it. Buttons are large enough for a finger. Nothing important requires dragging. Sliders are native ranges: arrows change them. Color is not the only way to tell two states apart.

If you ask the system to reduce motion, the ball will hold still, and no meaning is hidden in the movement.

Appearance can follow the system, or stay light, or stay dark. Quiet is not faint: body text meets a 4.5 to 1 contrast. You can zoom to 200 percent. A narrow phone still reflows. Phone, tablet, and wide each get their own layout, not a squeezed desktop.

Diagrams have a sentence saying what they show. Color is not the only way to tell two states apart.

Listen is Eve. On the first path she says the question and what to try, so a child who is not reading yet can still finish. Look closer and Keep looking are extra, not required. You can pause and move in the reading. A broken 0:00 is never shown.