<body class=>
<div class="container">
<div class="text">Text text .</div>
  </div> 
</body>
body, height {
  height: 100%;
}
body {
  background: linear-gradient(to right, transparent calc(50% + 1px), #fff calc(50% + 1px)), linear-gradient(to right, #fff calc(50% - 1px), lightgrey calc(50% - 1px));
}

html {
    top: 0%;
  left: -5%;
  -webkit-animation: slide 1s 1 ease-out
}

@-webkit-keyframes slide {
  0% {
    width: 0;
  }
  100% {
    width: 100%;
  }
}

.text {
  background: white;
  text-align: center;
  font-family: 'Montserrat', sans-serif;
  font-weight: 900;
  color: #333;
  font-size: 40px;
  padding: 50px;
  max-width: 50%;
  margin: 100px auto 0;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.