问包装中的中心形式

EN

.newsletter {
  background: none;
}

.newsletter form {
  max-width: 720px;
}

.newsletter .newsletter__label {
  display: inline-block;
  font-family: 'Josefin Slab' !important;
  font-size: 18px;
  font-style: normal;
  height: 25px;
  line-height: 25px;
  padding: 2px 0;
  position: static;
  text-transform: uppercase;
  vertical-align: top;
  width: auto;
  letter-spacing: 1px;
}

.newsletter .newsletter__input {
  border: none;
  border-bottom: 1px solid #000;
  color: #000;
  font-size: 17px;
  font-style: normal;
  margin-left: 5px;
  margin-right: 5px;
  padding: 0;
  vertical-align: bottom;
  width: 250px;
  text-transform: uppercase;
  font-family: Ubuntu !important;
  padding: 2px 0;
}

.newsletter .newsletter__input:not(:root:root) {
  padding: 0;
}

.input-group-field,
.input-group-btn {
  vertical-align: bottom;
  width: auto;
  padding-top: 5px;
}

.newsletter .input-group .btn,
.newsletter .input-group .btn--secondary,
.newsletter .input-group .input-group-field {
  font-family: Ubuntu !important;
}

.newsletter .input-group .input-group-field {
  font-family: Ubuntu !important;
  height: 25px;
  letter-spacing: 1px;
}

.newsletter .input-group .input-group-field:focus {
  outline: none;
}

.newsletter .input-group .btn {
  border: medium none;
  line-height: normal !important;
  padding: 0 12px !important;
  vertical-align: top;
  height: 20px;
  margin: 0;
  width: auto;
  text-decoration: none;
  text-align: center;
  vertical-align: middle;
  white-space: normal;
  font-family: 'Ubuntu', sans-serif;
  cursor: pointer;
  border: 1px solid transparent;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  -o-user-select: none;
  user-select: none;
  -webkit-appearance: none;
  -moz-appearance: none;
  border-radius: 0;
  background-color: #1c1d1d;
  color: #fff;
  -webkit-transition: background-color 0.15s ease-out;
  -moz-transition: background-color 0.15s ease-out;
  -ms-transition: background-color 0.15s ease-out;
  -o-transition: background-color 0.15s ease-out;
  transition: background-color 0.15s ease-out;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  font-weight: 300;
  font-size: 13px !important;
}

.newsletter .input-group .btn:hover {
  opacity: 0.8;
}

.newsletter .newsletter__input::-webkit-input-placeholder {
  color: #cbcbcb;
  opacity: 0.5;
}

.newsletter .newsletter__input:-moz-placeholder {
  color: #cbcbcb;
  opacity: 0.5;
}

.newsletter .newsletter__input::-moz-placeholder {
  color: #cbcbcb;
  opacity: 0.5;
}

.newsletter .newsletter__input:-ms-input-placeholder {
  color: #cbcbcb;
  opacity: 0.5;
}

.newsletter .newsletter__input::-ms-input-placeholder {
  color: #cbcbcb;
  opacity: 0.5;
}

.newsletter .input-group-field,
.newsletter .input-group-btn {
  display: inline-block;
  vertical-align: top;
}
#mc-embedded-subscribe-form {
  margin:auto
}

  <link rel="stylesheet" type="text/css" href="https://fonts.googleapis.com/css?family=Ubuntu:300,400,700,400italic">
  <link rel="stylesheet" type="text/css" href="https://fonts.googleapis.com/css?family=Josefin+Slab:400,700">
<div class="row">
  <div class="col-md-12 centered">
    <div class="newsletter">
      <div class="wrapper">
        <form id="mc-embedded-subscribe-form" method="post" name="mc-embedded-subscribe-form" target="_blank">
          <div class="newsletter--form">
            <div class="input-group">
              <label class="newsletter__label hidden-label" for="Email">Join our Family For Updates</label> &nbsp;
              <input class="input-group-field newsletter__input" id="Email" name="EMAIL" placeholder="Email Address" type="email" value=""> &nbsp;
              <span class="input-group-btn">
                  <button type="submit" class="btn newsletter__submit" name="subscribe" id="Subscribe">
                    <span class="newsletter__submit-text--large">SUBSCRIBE</span>
              <span class="newsletter__submit-text--small">
                      <span class="icon icon-arrow-right" aria-hidden="true"></span>
              </span>
              </button>
              </span>
            </div>
          </div>
        </form>
      </div>
    </div>
  </div>
</div>

.newsletter form{
   width: 30%;
   margin: auto;
}

.newsletter form {
  max-width: 720px;
  margin: auto;
}