Bootstrap 4

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.2/css/bootstrap.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.2/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootswatch/3.3.7/flatly/bootstrap.min.css">
 
<div class="col-md-12 tableDiv"  >
     <table class="table table-stripedcf" >
      <thead class="table-bordered">
        <tr>
          <th>Column1</th>
          <th>Column2</th>
          <th>Column3</th>
          <th>Column4</th>
          <th>Column5</th>
          <th>Column6</th>
        
        </tr>
      </thead>
      <tbody >
        <tr>
          <td > FIRST</td>
          <td >asdasdfasf</td>
          <td >fsdf</td>
          <td>sdfsfd</td>
          <td>sdfs</td>
          <td>fsdfsdf</td>
        </tr>
            <tr>
          <td > asdf</td>
          <td >asdfa</td>
          <td >fsdf</td>
          <td>sdfsfd</td>
          <td>sdfs</td>
          <td>fsdfsdf</td>
        </tr>
            <tr>
          <td > asdf</td>
          <td >asdfa</td>
          <td >fsdf</td>
          <td>sdfsfd</td>
          <td>sdfs</td>
          <td>fsdfsdf</td>
        </tr>
            <tr>
          <td > asdf</td>
          <td >asdfa</td>
          <td >fsdf</td>
          <td>sdfsfd</td>
          <td>sdfs</td>
          <td>fsdfsdf</td>
        </tr>
            <tr>
          <td > asdf</td>
          <td >asdfa</td>
          <td >fsdf</td>
          <td>sdfsfd</td>
          <td>sdfs</td>
          <td>fsdfsdf</td>
        </tr>
            <tr>
          <td > asdf</td>
          <td >asdfa</td>
          <td >fsdf</td>
          <td>sdfsfd</td>
          <td>sdfs</td>
          <td>fsdfsdf</td>
        </tr>
            <tr>
          <td > asdf</td>
          <td >asdfa</td>
          <td >fsdf</td>
          <td>sdfsfd</td>
          <td>sdfs</td>
          <td>fsdfsdf</td>
        </tr>
            <tr>
          <td >...

CSS

.table-bordered tr {
  position: fixed;
  z-index:1;
  top: 50px;
  background: #fff;
}

.tableDiv{
  margin-top:80px
}