Reset the resolution back to normal by pressing Ctrl + Shift + 0
Sometime the Chromebook's ENTIRE DISPLAY appears zoomed in, or magnified. This can be changed with the keys Ctrl and Shift and + (to zoom in) or Ctrl and Shift and - (to zoom out). Pressing Ctrl + Shift + 0 sets the display back to normal.
You can also make a specific PAGE bigger or smaller by pressing Ctrl and + or Ctrl and -. Page zoom is reset by pressing Ctrl + 0.