移动设备上显示错误尺寸的汉堡包图标

Question

我在网站上使用hmaburger图标时遇到了一些麻烦。它在较大的视口上看起来很好，但是当您将窗口调整为较小（或在移动设备上查看）时，条形的大小变得不一致且非常难看。

我需要使用vmin大小调整，因此它完全响应但无法弄清楚问题是什么。有没有办法解决这个问题？

$(document).ready(function() {
  $('.menu-icon').click(function() {
    $(this).toggleClass('open');
  });
});

.container {
  display: block;
  position: absolute;
  left: 5vmin;
  top: 5vmin;
}
.menu-icon {
  width: 6.76vmin;
  height: 5vmin;
  position: relative;
  bottom: 0;
  right: 0;
  -webkit-transform: rotate(0deg);
  -moz-transform: rotate(0deg);
  -o-transform: rotate(0deg);
  transform: rotate(0deg);
  cursor: pointer;
}
.menu-icon span {
  display: block;
  position: absolute;
  height: 1vmin;
  width: 100%;
  background: rgb(25, 27, 29);
  border-radius: 1vmin;
  opacity: 1;
  left: 0;
  -webkit-transform: rotate(0deg);
  -moz-transform: rotate(0deg);
  -o-transform: rotate(0deg);
  transform: rotate(0deg);
  -webkit-transition: 0.5s ease-in-out;
  -moz-transition: 0.5s ease-in-out;
  -o-transition: 0.5s ease-in-out;
  transition: 0.5s ease-in-out;
}
.menu-icon span:nth-child(1) {
  top: 0;
}
.menu-icon span:nth-child(2),
.menu-icon span:nth-child(3) {
  top: 2vmin;
}
.menu-icon span:nth-child(4) {
  top: 4vmin;
}
.menu-icon.open span:nth-child(1),
.menu-icon.open span:nth-child(4) {
  top: 2vmin;
  width: 0%;
  left: 50%;
}
.menu-icon.open span:nth-child(2) {
  -webkit-transform: rotate(225deg);
  -moz-transform: rotate(225deg);
  -o-transform: rotate(225deg);
  transform: rotate(225deg);
}
.menu-icon.open span:nth-child(3) {
  -webkit-transform: rotate(-225deg);
  -moz-transform: rotate(-225deg);
  -o-transform: rotate(-225deg);
  transform: rotate(-225deg);
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.2/jquery.min.js"></script>
<div class="container">
  <div class="menu-icon">
    <span></span>
    <span></span>
    <span></span>
    <span></span>
  </div>
</div>