html {
    width: 100%;
  }
  body {
    background: #f5f5f5;
    margin: 50px auto;
    width: 512px;
  }
  
  .mdl-button--file {
    input {
      cursor: pointer;
      height: 100%;
      right: 0;
      opacity: 0;
      position: absolute;
      top: 0;
      width: 300px;
      z-index: 4;
    }
  }
  
  .mdl-textfield--file {
    .mdl-textfield__input {
      box-sizing: border-box;
      width: calc(100% - 32px);
    }
    .mdl-button--file {
      right: 0;
    }
  }