Initial styles.
Initial functionality.
Display incomplete items on top on load and when adding a new item.
Sort by category, then sort by date.
#5 space between checkboxes should not turn into | cursor
Fixed not showing the 1st element when the list is empty.
Made completed items non-editable
Enter and escape end edit.
deleted to-do item should animate out #4
Add animation.
Made head floating, fixed height for scrolling, and new to-do item should animate in #3