The SIZE attribute has some limitations: In Opera, Mosaic and
IE versions 3.0 and before, there are no restrictions on the SIZE attribute.
If you specify a pixel size, it will be rendered. In all versions of Netscape and
in IE 4.0+, the SIZE attribute is limited to 100 pixels - values above this amount
will be rendered as SIZE=100 in these browsers.
Table showing different values for HR SIZE attribute: