修改顶部导航，改成fixed定位

Author: junhey

src/components/listContent.vue

@@ -38,6 +38,7 @@
 <style lang="scss" scoped>
     .list-content{
         position: relative;
+        padding-top:40px;
         .list-item{
             position: relative;
             font-size:0;

src/components/listHeader.vue

@@ -1,5 +1,5 @@
 <template>
-    <div>
+    <div class="fixed">
         <div class="nav">
             <ul>
                 <li :class="navSelect=='all'?'active':''" @click="selectTab" data-navSelect='all'>全部</li>
@@ -27,9 +27,16 @@
     }
 </script>
 <style lang="scss" scoped>
+    .fixed{
+        position:fixed;
+        width:100%;
+        top:0;
+        z-index:999;
+    }
     .nav {
         color: #fff;
         background-color: #333;
+        display:block;
         ul{
             font-size: 0;
             li{