"Input Submit" Cross-browser compatibility

Answer 1

This is because default styles on HTML elements like input buttons and H1 and UL and LI and so forth are subject to the browser developer's whim. You can minimize the disruption by using a reset stylesheet. That said, you may get better results by using <button type="submit" value="Share">Share</button> instead of an input (with a type of button), and setting the styles on that.