[Reptur]

I suggest:

Property: auto-resize

Values:

none: No auto-resizing.

horizontal: Auto-resizes horizontally based on content.

vertical: Auto-resizes vertically based on content.

both: Auto-resizes both horizontally and vertically based on content.

Usage:

  textarea {
      auto-resize: vertical;
  }

  input {
      auto-resize: both;
  }