.btn-square-slant {
    display: inline-block;
    position: relative;
    padding: 0.5em 1.4em;
    text-decoration: none;
    background: #3ea5ff;/*ボタン色*/
    color: #FFF;
    border-bottom: solid 5px #006ccb;/*ボタン色より暗めに*/
    border-right: solid 5px #5375bd;/*ボタン色より暗めに*/
  }
  
  .btn-square-slant:before {  
    content: " ";
    position: absolute;
    bottom: -5px;
    left: -1px;
    width: 0;
    height: 0;
    border-width: 0 6px 6px 0px;
    border-style: solid;
    border-color: transparent;
    border-bottom-color: #FFF;
  }
  
  .btn-square-slant:after {  
    content: " ";
    position: absolute;
    top: -1px;
    right: -5px;
    width: 0;
    height: 0;
    border-width: 0px 6px 6px 0px;
    border-style: solid;
    border-color: #FFF;
    border-bottom-color: transparent;
  }
  
  .btn-square-slant:active {
    /*ボタンを押したとき*/
    border:none;
    -webkit-transform: translate(6px,6px);
    transform: translate(6px,6px);
  }
  
  .btn-square-slant:active:after, .btn-square-slant:active:before {
    content: none;/*ボタンを押すと線が消える*/
  }
  

  .btn-flat-border {
    display: inline-block;
    padding: 0.3em 1em;
    text-decoration: none;
    color: #67c5ff;
    border: solid 2px #67c5ff;
    border-radius: 3px;
    transition: .4s;
  }
  
  .btn-flat-border:hover {
    background: #67c5ff;
    color: white;
  }