老师帮忙批改下，底部的文字无法居中，图片不能全部显示出来被放大了

<style type="text/css">
* {
    margin: 0px;
    padding: 0px;
   }
 
.top {
    width: 100%;
    height: 100px;
    background-color: black;
    position:fixed;
    top: 0px;
    margin: 0 auto;
}
 
im {
    float: left;
    cursor: pointer;
}
 
ul {
    float: right;
}
.im1{margin-top: 100px;
     margin-bottom: 100px;
     width:100%;
     background-repeat: no-repeat;}
ul li {
       list-style-type: none;
       display: inline;
       color: #fff;
       text-align: center;
       line-height: 100px;
       font-size: 25px;
       font-family: "微软雅黑";
       margin: 30px;
}
 .nv2 li {
        
       list-style-type: none;
       display: inline-block;
       color: #fff;
       font-size: 25px;
       font-family: "微软雅黑";
       margin: 30px;
        
}
.foot{
    width: 100%;
    height: 100px;
    background-color: black;
    position: fixed;
    text-align: center;
    line-height: 100px;
    bottom: 0px;
    left: 0px;
    word-spacing:50px;
}
</style>
</head>
<body>
    <div class="top">
        <img alt=""
            src="http://img1.sycdn.imooc.com/climg//58c0d2d900016ce303000100.png">
        <ul>
            <li>课程</li>
            <li>职业路径</li>
            <li>实践</li>
            <li>猿问</li>
            <li>手记</li>
        </ul>
     </div>
     <div class="img1">
     <img alt="" src="http://img1.sycdn.imooc.com/climg//58c0eda50001e12416000480.jpg">
     <img alt="" src="http://img1.sycdn.imooc.com/climg//58c0edb80001c9f216000480.jpg">
     <img alt="" src="http://img1.sycdn.imooc.com/climg//58c0edc9000100d516000480.jpg">
     </div>
     <div class="foot">
     <ul class="nv2">
            <li>课程</li>
            <li>职业路径</li>
            <li>实践</li>
            <li>猿问</li>
            <li>手记</li>
        </ul></div>
</body>