1. Split now is so big make it 3/4 its

Question

1. Split now is so big make it 3/4 its

current size.
2. All buttons have sharp corners try to make a rounded border styles.
3. The green color looks dark, try to make it lighter green.
4. Options text is also big reduce it a bit.
5. Detach the "browse" button from the file field.
6. The current selection color of the menu is on both "split" and "checksum" why?, it should only show the nav that you are currently on.
And rest is good, well done