You can set the height and width of the checkbox, but the results are inconsistent. Changing the size of checkboxes You must be using Firefox so you will not see the enlarged checkboxes ..they will just look normal but you should see the reduced ones. A checkbox is a form element that allows the user to select multiple options from a range of options. Set the height and width attribute to 25px and initial background color to black. Created 12/2005; Updated 11/2009. The technique is the same as in the image-based method, but because the width is set relative to the font size in line 3 we must restore the font size in line 6, as browsers use a smaller font size for checkboxes and radio buttons by default. There should usually be a space between the and the