When zooming in, why does the footer overlap its preceding content
问题 here is the sample html: <div id = "mainWrapperDiv"> <div id = "mainDiv"> <div> testing </div> </div> </div> <div id = "footerDiv"> </div> its css: * { padding: 0px; margin: 0px; } body, html { height: 100% } div { border: none; } #mainWrapperDiv { min-height: 100%; height: 100%; margin-bottom: -200px; } #mainDiv { margin: 0px auto 0px auto; width: 1000px; min-height: 500px; background: lightgreen; } #footerDiv { height: 200px; width: 100%; position: relative; clear: both; background: