<div class='subscribe'>
    <div class='subscribe__image'>
      <img src='https://user-images.githubusercontent.com/23297041/53905033-9570ad00-4058-11e9-809d-c090c0468264.png'> 
    </div>
    <div class='subscribe__text'>
      <p class='heading'>Stay tuned</p>
      <p class='subheading'>Praesent commodo cursus magna, vel scelerisque nisl consectetur et.</p>
    </div>
    <form class='form' id='form'>
      <input class='subscribe__input input' type='email' placeholder='Enter your email' required>
      <input class='subscribe__btn btn' type='submit' value='Subscribe'>
    </form>
  </div>
$black: #343c41;
$white: #ffffff;
$blue: #1b9cfc;
$green: #53ce67;

* {
  box-sizing: border-box;
}

body {  
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  font-family: 'Lato', sans-serif;
  background: url('https://user-images.githubusercontent.com/23297041/54643510-2196c180-4aa8-11e9-9d98-06c2bdc59761.png');
  background-size: cover;
}

img {
  max-width: 100%;
  height: auto;
}

p {
  margin: 12px 0;
}

.heading {
  font-size: 42px;
  font-weight: 700;
  color: $black;
}

.subheading {
  font-size: 18px;
  line-height: 24px;
  color: lighten($black, 50%);
}

.form {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.input {
  width: auto;
  padding: 10px 8px;
  border: 1.5px solid lighten($black, 60%);
  border-radius: 4px;
  text-align: center;
  transition: all .4s linear;
  
  &::placeholder {
    opacity: 0.35;
  }
  
  &:focus,
  &:hover,
  &:valid {
    outline: none;
    border: 1.5px solid lighten($blue, 30%);
  }
}

.btn {
  padding: 12px 32px;
  background-color: $blue;
  font-size: 17px;
  letter-spacing: 0.5px;
  color: $white;
  border: none;
  border-radius: 6px;
  transition: all .4s ease-in-out;
  opacity: 0.45;
  cursor: pointer;
  
  &--active {
    animation: buttonActive .3s both;
  }
  
  &--success {
    animation: buttonSuccess .4s both;
  }
  
  &:focus {
    outline: none;
  }
}

.subscribe {
  display: flex;
  flex-direction: column;
  align-items: center;
  min-width: 625px;
  min-height: 465px;
  border-radius: 9px;
  background-color: $white;
  box-shadow: 13px 15px 79px 6px rgba(0,0,0,0.1);
  
  &__image {
    position: relative;
    max-width: 80px;
    margin: 50px 10px 0;
    
    &--success:after {
      position: absolute;
      top: -6px;
      right: -6px;
      width: 26px;
      height: 26px;
      background-image: url('https://user-images.githubusercontent.com/23297041/53911760-6c581880-4068-11e9-90ab-ac45ae3b4aa8.png');
      background-size: cover;
      content: '';
      animation: slideUp .3s ease-out;
    }
  }
  
  &__text {
    max-width: 300px;
    margin-bottom: 30px;
    text-align: center;
  }
  
  &__input {
    min-width: 250px;
    margin-bottom: 15px;
  }
  
  &__btn {
    width: 180px;
  }
}


@keyframes buttonActive {
  to {
    transform: translateY(-1px);
    opacity: 1;
  }
}

@keyframes buttonSuccess {
  from {
    opacity: 1;
  }
  to {
    width: 230px;
    background-color: $green;
    opacity: 1;
  }
}

@keyframes slideUp {
  from {
    transform: translateY(15px);
  }
}

@media screen and (max-width: 680px) {
  .subscribe {
    min-width: 350px;
  }
}
View Compiled
const form = document.getElementById('form')
const formInput = document.querySelector('.subscribe__input')
const formBtn = document.querySelector('.subscribe__btn')
const subscribeImg = document.querySelector('.subscribe__image')

formInput.addEventListener('input', () => {
  formInput.checkValidity() ? formBtn.classList.add('btn--active') : formBtn.classList.remove('btn--active')
})

form.addEventListener('submit',e => {
  e.preventDefault()
  
  subscribeImg.classList.add('subscribe__image--success')
  formBtn.classList.add('btn--success')
  formBtn.value = "You're on the list! 👍"
  
  formInput.disabled = true
  formBtn.disabled = true
})
View Compiled
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