我已经编写了以下HTML代码，适用于在Chrome，Firefox，Safari和Opera上运行良好但在Internet Explorer上无效的表单。以下是代码
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<style>
input[type=text] {
height:32px;
width:522px;
margin: 8px 0 0 0;
font-size:18px;
vertical-align:middle;
outline:#A349A4;
outline-width:2px;
}
input[type=text]:focus {
border: 1px;
border-color:#A349A4;
border-style:solid;
}
::-webkit-input-placeholder {
color: #C3C3C3;
}
:-moz-placeholder {
color: #C3C3C3;
}
:-ms-input-placeholder {
color: #C3C3C3;
}
</style>
</head>
<body>
<form>
<input id="search" autofocus="autofocus" autocomplete="off" type="text" spellcheck="false" title="Enter What You Want To Search." lang="en" dir="ltr" placeholder="Search Something Good." tabindex="1">
<br>
</form>
</body>
</html>
我在Windows上使用IE8 7.任何人都建议我这是什么兼容性问题？