文字横向滚动marquee

<div style="200px; height:300px">

<marquee behavior="scroll" contenteditable="true" onstart="this.firstChild.innerHTML+=this.firstChild.innerHTML;" scrollamount="3" width="100" onmouseover="this.stop();" onmouseout="this.start();">
这里是要滚动的内容
</marquee>
</div>