我有：
/* History */
.mask3 {
text-align: center;
}
section#history {
padding-bottom: 0;
}
section#history h1 {
font-size: 3em;
margin-bottom: 1em;
margin-top: 0.5em;
}
section#history hgroup h2 {
margin-top: 1em;
text-transform: capitalize;
}
section#history hgroup h3 {
margin-top: .35em;
font-family: 'Patua One', cursive;
}
section#history .entry-content {
margin: 1em 0 2.5em;
}
section#history .align {
text-align: center;
margin-top: 10px;
font-size: 6em;
}
/* history Image Hover */
.mask3 img {
margin: 0 auto;
max-width: 100%;
display: block;
-ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=70)";
filter: alpha(opacity=80);
opacity: 0.6;
box-shadow: 1px 1px 10px rgba(0, 0, 0, 0.2);
-webkit-transition: all 0.3s ease-in-out;
-moz-transition: all 0.3s ease-in-out;
-o-transition: all 0.3s ease-in-out;
-ms-transition: all 0.3s ease-in-out;
transition: all 0.3s ease-in-out;
}
.mask3 img:hover {
-ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=99)";
filter: alpha(opacity=99);
opacity: 1;
}我试图这样做：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>JS Bin</title>
</head>
<body>
<div class="row">
<div class="span3">
<div class="mask3">
<a href="img/profile-01.jpg" rel="prettyPhoto">
<img src="img/profile-01.jpg" alt="">
</a>
</div>
<div class="inside">
</div>
<!-- /.inside -->
</div>
<!-- /.span3 -->
<div class="span3">
<div class="mask3">
<a href="img/profile-01.jpg" rel="prettyPhoto">
<img src="img/profile-01.jpg" alt="">
</a>
</div>
<div class="inside">
</div>
<!-- /.inside -->
</div>
<!-- /.span3 -->
<div class="span3">
<div class="mask3">
<a href="img/profile-01.jpg" rel="prettyPhoto">
<img src="img/profile-01.jpg" alt="">
</a>
</div>
<div class="inside">
</div>
<!-- /.inside -->
</div>
<!-- /.span3 -->
</div>
</body>
</html>我收到一个未定义的警报，我该如何解决？
问题是我没有得到输入值