form_transition.scss

input[type='email'] {
    width: 68%;

    &:focus {
      // outline: 1px dotted;
      border-bottom: 1px solid $dodger-blue;
    }

    // When clicking in this element, light up the button
    &:focus ~ input[type='submit'] {
      transition: background-color 0.3s;
      background-color: $dodger-blue;
    }
  }