SOURCE

<div class="terminal">
  <p>Hello World!</p>
</div>

@import url("https://fonts.googleapis.com/css?family=Fira+Sans:300");
html,
body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: #9664e1;
  font-family: 'Fira Sans', sans-serif;
  font-size: 12px;
}
*,
*:before,
*:after {
  box-sizing: border-box;
}
.terminal,
.terminal:before,
.terminal:after,
p:after {
  position: absolute;
}
.terminal {
  height: 80vh;
  width: 80vw;
  margin: 10vh 10vw;
  padding: 26px 4px 4px;
  border-radius: 5px;
  background: -webkit-linear-gradient(#f6f6f6, #d3d3d3 20px, #7e7e7e 20px, #7e7e7e 21px, #393456 21px);
  background: linear-gradient(#f6f6f6, #d3d3d3 20px, #7e7e7e 20px, #7e7e7e 21px, #393456 21px);
  box-shadow: 0 0 0 1px rgba(0,0,0,0.25);
  -webkit-transition: all 0.5s ease;
  transition: all 0.5s ease;
}
.terminal:before {
  content: " ";
  width: 10px;
  height: 10px;
  margin: -20px 0 0 5px;
  border-radius: 5px;
  background: #fc625d;
  box-shadow: 0 0 0 1px #de413e, 15px 0 #fec041, 15px 0 0 1px #dda035, 30px 0 #35cc4b, 30px 0 0 1px #28aa36;
}
.terminal:after {
  width: 100%;
  content: "Pure CSS Terminal";
  top: 0;
  text-align: center;
  color: #4c4c4c;
  line-height: 20px;
}
p {
  color: #fff;
}
p:before {
  content: "$";
  margin-right: 8px;
  opacity: 0.5;
  line-height: 18px;
}
p:after {
  -webkit-animation: blink 1s linear 1s infinite;
          animation: blink 1s linear 1s infinite;
  content: " ";
  width: 8px;
  height: 18px;
  margin-left: 1px;
  background: #fec041;
}
@-webkit-keyframes blink {
  0% {
    background: rgba(254,192,65,0);
  }
  50% {
    background: rgba(254,192,65,0);
  }
  51% {
    background: #fec041;
  }
  100% {
    background: #fec041;
  }
}
@keyframes blink {
  0% {
    background: rgba(254,192,65,0);
  }
  50% {
    background: rgba(254,192,65,0);
  }
  51% {
    background: #fec041;
  }
  100% {
    background: #fec041;
  }
}