iPhone Div背景图像居中

我的网站页脚有问题。

正如你在iPhone（Safari）上看到的那样，页脚图像显示不正确，并且跨越了网站的宽度。

这是页脚的代码：

.footer {
  width: 100%;
  height: 118px;
  background: #000000 url(../images/footer.png) top center !important;
  margin: 70px auto 0 auto;
}

<div class="footer">
  <div style="width:1100px;height:118px;margin:auto;">
    <div id="mc_embed_signup">
      <form action="http://SaveWithPride.us7.list-manage.com/subscribe/post?u=0beccc5a2d913b0527a748edc&amp;id=cb6e398bc5" method="post" id="mc-embedded-subscribe-form" name="mc-embedded-subscribe-form" class="validate" target="_blank" novalidate>
        <input type="email" value="" name="EMAIL" class="email footer-field" id="mce-EMAIL" placeholder="enter your text" onfocus="this.placeholder = ''" onblur="this.placeholder = 'enter your text'" required>
        <div class="clear"><input type="submit" value="Subscribe" name="subscribe" id="mc-embedded-subscribe" class="button footer-submit"></div>
      </form>
    </div>
    <div style="width:334px;height:118px;float:right;background:transparent;">
      <div class="socialtext">save with pride, socially:</div>
      <div class="twitter"></div>
      <div class="facebook"></div>
      <div class="footertext">© 2013 SaveWithPride.com&nbsp&nbspAll Rights Reserved.&nbsp&nbsp<a href="adamdworak.com">Design by A/D</a></div>
    </div>
  </div>
</div>

我在这里做错了什么？页脚背景（现在显示的）没有延伸到iPhone浏览器的边缘，似乎没有居中。我正在努力使它居中，并在我的电脑上显示100%的宽度。