style.css

html, body, div, header, h1, section, label, input, textarea, ul, li, footer {
  margin: 0;
  padding: 0;
}

body {
  width: 400px;
  font-size: 14px;
}

.wrapper {
  padding: 2%;
}

h1 {
  font-size: 24px;
  border-bottom: 1px solid #ccc;
  padding-bottom: 4%;
}

section {
  padding-top: 4%;
  padding-bottom: 6%;
}

li {
  list-style-type: none;
  padding-top: 2%;
}

.input.length {
  font-size: 14px;
}

.btn {
  display: inline-block;
  padding: 6px 12px;
  margin-bottom: 0;
  font-size: 14px;
  font-weight: 400;
  line-height: 1.42857143;
  text-align: center;
  white-space: nowrap;
  vertical-align: middle;
  -ms-touch-action: manipulation;
  touch-action: manipulation;
  cursor: pointer;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
  background-image: none;
  border: 1px solid #357ebd;
  border-radius: 4px;
  color: #fff;
  background-color: #428bca;
}

.btn:hover {
  background-color: #2d6ca2;
}

.hide {
  display: none;
}

textarea.show {
  resize: none;
  display: block;
  width: 100%;
  font-size: 18px;
  background-color: #eee;
  border-radius: 4px;
  border: 1px solid #eee;
  margin-bottom: 6%;
  padding-top: 2%;
  padding-bottom: 2%;
  position: relative;
}

.show:focus,
.btn:focus {
  outline: none;
}

.tooltip {
  position: absolute;
  background: #5cb85c;
  color: #fff;
  top: 140px;
  left: 20px;
  -webkit-animation: spring 0.3s ease-in-out 1;
  width: 200px;
  text-align: center;
  padding: 2%;
  font-size: 18px;
}

@-webkit-keyframes spring {
  0% {bottom: 75px; opacity:0; -webkit-transform: scale(0,0);}
  40% {top: 120px; opacity:1; -webkit-transform: scale(1.15,1.15);}
  60% {top: 140px; opacity:1; -webkit-transform: scale(1,1);}
  80% {top: 145px; opacity:1; -webkit-transform: scale(1.05,1.05);}
  100% {top: 140px; opacity:1; -webkit-transform: scale(1,1);}
}

.tooltip:after {
  content: '';
  width: 0;
  height: 0;
  border-top: 8px solid #5cb85c;
  border-left: 8px solid transparent;
  border-right: 8px solid transparent;
  position: absolute;
  left: 100px;
  bottom: -8px;
}