在CSS中使用转换样式的文字模糊

Question

我在下面的CSS中遇到问题。在类为front的div中，文本像在this image上一样模糊

我正在使用Chrome，但是在每个浏览器上我都看到相同的模糊文本。我想保留每个div，但是我不确定是什么使文本如此模糊。

如何修复它，使其不模糊？

JsFiddle

HTML和CSS

.main {
  margin: auto;
  height: auto;
  padding-top: 25px;
}

.panel {
  width: 45%;
  display: inline-block;
  margin: 14px;
}

.est {
  box-shadow: 0 0 0 #fff;
  background-color: transparent;
}

.flip .back {
    -webkit-transform: rotateY(360deg);
    -moz-transform: rotateY(360deg);
    -ms-transform: rotateY(360deg);
    -o-transform: rotateY(360deg);
    transform: rotateY(360deg);
}

#card-1,
#card-2,
#card-3,
#card-4,
#card-5 {
  height: 300px;
  width: 100%;
  margin: 0 auto;
  z-index: 1;
  display: inline-block;
  perspective: 700px;
}

h4,
.h4 {
  font-size: 20px;
}

body {
  font-size: 14px;
  font-family: Roboto, sans-serif;
  line-height: 1.35;
  color: #222;
  background: #f4f5f7;
  text-rendering: optimizeLegibility;
  padding: 0;
  left: 0;
  right: 0;
  transition-duration: 200ms;
  transition-timing-function: cubic-bezier(0.4, 0, 0.2, 1);
}

.front {
  -webkit-transform: rotateY(0);
  -moz-transform: rotateY(0);
  -ms-transform: rotateY(0);
  -o-transform: rotateY(0);
  transform: rotateY(0);
  z-index: 1;
}

.back,
.front {
  border: 1px solid #ddd;
  height: 100%;
  top: 0;
  transform-style: preserve-3d;
  backface-visibility: hidden;
}

.back,
.front,
.front .info-box,
.social-bar {
  position: absolute;
  left: 0;
  width: 100%;
}

.ease {
  -webkit-transition: all .45s ease-out;
  -moz-transition: all .45s ease-out;
  -ms-transition: all .45s ease-out;
  -o-transition: all .45s ease-out;
  transition: all .45s ease-out;
}

.e-i-f-about,
.front,
.p-class-earn,
.strike {
  overflow: hidden;
}

.back,
.flip .front {
  -webkit-transform: rotateY(180deg);
  -moz-transform: rotateY(180deg);
  -ms-transform: rotateY(180deg);
  -o-transform: rotateY(180deg);
  transform: rotateY(180deg);
}

.back,
.front {
  border: 1px solid #ddd;
  height: 100%;
  top: 0;
  transform-style: preserve-3d;
  backface-visibility: hidden;
}

.back,
.front,
.front .info-box,
.social-bar {
  position: absolute;
  left: 0;
  width: 100%;
}

.back {
  background-color: #fff;
  display: table;
  z-index: 2;
  font-size: 13px;
  line-height: 23px;
  padding: 10px 20px;
  height: 320px;
}

<div class="main pad-2">
  <center>
    <h4>Not blurred text</h4>
    <div class="panel e-b est" style="margin-top:0">
      <div class="wrapper">
        <div id="card-1">
          <div class="front ease">
            <a href="javascript:void(0)" class="open-1" id="open-1">Click</a>
            <div class="info-box">
              <div class="info">
                <h4>test1 blurred text</h4>
              </div>
            </div>
          </div>
          <div class="back ease">
            2nd text here
          </div>
        </div>
      </div>
    </div>
    <div class="panel e-b est" style="margin-top:0">
      <div class="wrapper">
        <div id="card-2">
          <div class="front ease">
            <a href="javascript:void(0)" class="open-2" id="open-2">Click</a>
            <div class="info-box">
              <div class="info">
                <h4>test2 blurred text</h4>
              </div>
            </div>
          </div>
          <div class="back ease">
            2nd text here
          </div>
        </div>
      </div>
    </div>
  </center>
</div>