bootstrap custom select

 <div class="form-group">
  <label for="sel1">Select list:</label>
  <select class="form-control" id="sel1">
    <option>1</option>
    <option>2</option>
    <option>3</option>
    <option>4</option>
  </select>
</div> 

<form>
  <div class="form-group">
    <label for="exampleFormControlFile1">Example file input</label>
    <input type="file" class="form-control-file" id="exampleFormControlFile1">
  </div>
</form>

<div class="form-check">
  <input type="checkbox" class="form-check-input" id="exampleCheck1">
  <label class="form-check-label" for="exampleCheck1">Check me out</label>
</div>

<div class="form-group">
    <label for="exampleFormControlSelect1">Example select</label>
    <select class="form-control" id="exampleFormControlSelect1">
      <option>1</option>
      <option>2</option>
      <option>3</option>
      <option>4</option>
      <option>5</option>
    </select>
  </div>
  <div class="form-group">
    <label for="exampleFormControlSelect2">Example multiple select</label>
    <select multiple class="form-control" id="exampleFormControlSelect2">
      <option>1</option>
      <option>2</option>
      <option>3</option>
      <option>4</option>
      <option>5</option>
    </select>
  </div>

  <form>
  <select name="cars" class="custom-select">
    
  <option selected>Custom Select Menu</option>
    <option 
  value="volvo">Volvo</option>
    <option value="fiat">Fiat</option>
    
  <option value="audi">Audi</option>
  </select>
</form>