When highlighting any field for editing [example: “Edit text” / size], the input field turns a very pale blue color. It’s hard to see that the field is actually highlighted, and a stray mouse click can deselect the edit field.
A very simple improvement would be to make the color of a highlighted edit field a more visible color than the very pale blue that the editor now displays. Yellow highlight would be good, or a slightly deeper blue, or just about any color that’s more visible than we we see now.