scrollTop when the CSS flex-direction property is set to column-reverse

• Summary
  • When flex-direction: column-reverse
    • The reference point for scrollTop is the very bottom of the scroll
    • scrollTop takes values from -n to 0
    • When the scroll bar is at the very top, scrollTop === -n
    • When the scroll bar is at the very bottom, scrollTop === 0
• The general case
  • When the scroll bar is at the very top
    • scrollTop === 0
  • When the scroll bar is at the very bottom
    • scrollTop === scrollHeight - clientHeight
• When flex-direction: column-reverse is applied via CSS
  • When the scroll bar is at the very top
    • -scrollTop === scrollHeight - clientHeight
  • When the scroll bar is at the very bottom
    • scrollTop === 0

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