Edit in JSFiddle

<div class="row">
  <div class="small-12 medium-6 columns">
    <div class="input-container">
      <input type="text" placeholder="First Name" required>
      <label>First Name</label>
      <i class="fa fa-check"></i>
    </div>
  </div>
  <div class="small-12 medium-6 columns">
    <div class="input-container">
      <input type="text" placeholder="Last Name" required>
      <label>Last Name</label>
      <i class="fa fa-check"></i>
    </div>
  </div>
</div>

<div class="row">
  <div class="small-12 medium-6 columns">
    <div class="input-container">
      <input type="email" pattern="^[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,4}$" placeholder="Email Address" required>
      <label>Email Address</label>
      <i class="fa fa-check"></i>
    </div>
  </div>
  <div class="small-12 medium-6 columns">
    <div class="input-container">
      <input type="tel" pattern="^(\+\d{1,2}\s)?\(?\d{3}\)?[\s.-]\d{3}[\s.-]\d{4}$" placeholder="Phone Number" required>
      <label>Phone Number - ###-###-####</label>
      <i class="fa fa-check"></i>
    </div>
  </div>
</div>

<div class="row">
  <div class="small-12 medium-12 columns">
    <div class="input-container">
      <input type="text" placeholder="Street Address" required>
      <label>Street Address</label>
      <i class="fa fa-check"></i>
    </div>
  </div>
</div>

<div class="row">
  <div class="small-12 medium-4 columns">
    <div class="input-container">
      <input type="text" placeholder="City" required>
      <label>City</label>
      <i class="fa fa-check"></i>
    </div>
  </div>
  <div class="small-12 medium-4 columns">
    <div class="input-container">
      <input pattern="[A-Za-z]{2}" type="text" placeholder="State" required>
      <label>State - ex. NY</label>
      <i class="fa fa-check"></i>
    </div>
  </div>
  <div class="small-12 medium-4 columns">
    <div class="input-container">
      <input pattern="[0-9]{5,10}" placeholder="Zip" required>
      <label>Zip</label>
      <i class="fa fa-check"></i>
    </div>
  </div>
</div>

.input-container,
.input-container > input,
.input-container > label {
  box-sizing: border-box;
  line-height: 42px;
  height: 46px; /* This height is important and used throughout */
  width: 100%;
  font-size: 1rem;
  display: inline-block;
}

.input-container {
  position: relative;
}

.input-container input {
  position: absolute;
  background-color: #eaeaea;
  border: none;
  padding: 0 8px;
  outline: none;
}

.input-container > label {
  display: block;
  position: absolute;
  padding: 0px 8px;
  top: 46px; /* Must match the height of the element */
  overflow-y: hidden;
  height: 0;
  color: #eaeaea;
  background-color: #eaeaea;
  border-top-width: 0px;
  border-top-style: solid;
  border-top-color: #ffffff;
  border-bottom-width: 2px;
  border-bottom-style: solid;
  border-bottom-color: #777777;
  -webkit-transition: margin-top 0s ease-in, border-top 0s linear 0s;
  -moz-transition: margin-top 0s ease-in, border-top 0s linear 0s;
  -o-transition: margin-top 0s ease-in, border-top 0s linear 0s;
  transition: margin-top 0s ease-in, border-top 0s linear 0s;
}

/* Hide the input on focus, since the label is now showing */
.input-container input:focus[placeholder]::-webkit-input-placeholder {
  opacity: 0;
}

.input-container input:focus + label {
  margin: 0px 0;
  top: 0;
  margin-top: 46px;
  height: 46px;
  z-index: 100;
  border-top-width: 2px;
  border-top-color: #c77768;
  border-bottom-color: transparent;
  color: #8e8e8e;
  -webkit-transition: color 0.05s 0.02s, margin-top 0.07s ease-out, border-top 0s linear 0.069s;
  -moz-transition: color 0.05s 0.02s, margin-top 0.07s ease-out, border-top 0s linear 0.069s;
  -o-transition: color 0.05s 0.02s, margin-top 0.07s ease-out, border-top 0s linear 0.069s;
  transition: color 0.05s 0.02s, margin-top 0.07s ease-out, border-top 0s linear 0.069s;
}

.input-container input:valid:focus + label {
  border-top-color: #73c768;
  border-bottom-color: transparent;
  color:#8e8e8e;
  -webkit-transition: color 0.05s 0.02s, margin-top 0.07s ease-out, border-top 0s linear 0.069s;
  -moz-transition: color 0.05s 0.02s, margin-top 0.07s ease-out, border-top 0s linear 0.069s;
  -o-transition: color 0.05s 0.02s, margin-top 0.07s ease-out, border-top 0s linear 0.069s;
  transition: color 0.05s 0.02s, margin-top 0.07s ease-out, border-top 0s linear 0.069s;
}

.input-container input:valid + label {
  border-top-color: transparent;
  border-top-width: 2px;
  border-bottom-color: #ffffff;
  -webkit-transition: margin-top 0s ease-in, border-top 0s linear 0s;
  -moz-transition: margin-top 0s ease-in, border-top 0s linear 0s;
  -o-transition: margin-top 0s ease-in, border-top 0s linear 0s;
  transition: margin-top 0s ease-in, border-top 0s linear 0s;
}


/* Basic styling */
body {
  width: 80%;
  height: 460px;
  margin: 3em auto;
  background-color: #ffffff;
  font-family: Arial;
  font-size: 16px;
  overflow-y: hidden;
}

.input-container {
    margin-bottom: 2.6em;
  }

@media (min-width: 640px) {
  .input-container {
    margin-bottom: 0em;
  }

  .row {
     margin-bottom: 2.6em;
  }
}

.input-container input:valid {
  box-shadow: none;
}

.input-container input:invalid {
  outline: none;
  -moz-box-shadow: none;
  box-shadow: none;
}

.input-container input:focus {
  outline: none;
  border: none;
  box-shadow: none !important;
  background-color: #eaeaea;
}

.input-container input::-webkit-input-placeholder {
  color: #666666;
}

/* Icons 
   These are a nice addition, though not required
*/
.input-container i {
  position: absolute;
  z-index: 110;
  right: 0.5em;
  line-height: 46px;
  color: #73c768;
  font-size: 1.5em;
  opacity: 0;
  display: none;
  transition: opacity 0.2s linear:
}

.input-container input:valid ~ i {
  opacity: 1;
  transition: opacity 0.2s linear;
  display: block;
}

.input-container input:valid:focus ~ i {
  opacity: 0;
}