如何中心引導形式

Question

我有這樣的形式：

<form style="margin-top:20px"> 

      <div class="row form-group"> 
       <div class="col-lg-3"> 
        <label for="exampleInputEmail1">Original Amount</label> 
        <div class="input-group"> 
         <div class="input-group-addon" id="OriginalAmountAddon">$</div> 
         <input type="text" class="form-control" id="exampleInputAmount" placeholder="Amount"> 
        </div> 
       </div> 

       <div class="col-lg-3"> 
        <label for="exampleInputEmail1">Billing Amount</label> 
        <div class="input-group"> 
         <div class="input-group-addon" id="BillingAmountAddon">$</div> 
         <input type="text" class="form-control" id="exampleInputAmount" placeholder="Amount"> 
        </div> 
       </div> 
      </div> 

      <div class="row form-group"> 
       <div class="col-lg-3"> 
        <label for="exampleInputEmail1">Original Currency Code</label> 
        <div class="input-group"> 
         <div class="input-group-addon" id="OriginalCurrencyAddon">$</div> 
         <select class="form-control" id="OriginalCurrencySelect"> 
          <option value="$">USD</option> 
          <option value="€">EUR</option> 
          <option value="£">GBP</option> 
          <option value="₪">ILS</option> 
         </select> 
        </div> 
       </div> 

       <div class="col-lg-3"> 
        <label for="exampleInputEmail1">Billing Currency Code</label> 
        <div class="input-group"> 
         <div class="input-group-addon" id="BillingCurrencyAddon">$</div> 
         <select class="form-control" id="BillingCurrencySelect"> 
          <option value="$">USD</option> 
          <option value="€">EUR</option> 
          <option value="£">GBP</option> 
          <option value="₪">ILS</option> 
         </select> 
        </div> 
       </div> 
      </div></form> 

它看起來像這樣：

我想在中心整個窗體，怎麼樣？我是否需要分別居中每行？另外一個問題，比如我想要的「Supllier賬戶」字段與上述兩個字段的長度相同，如何？

Answer 1

這基本上是一個已經被問過很多次，問題的副本..

Center a column using Twitter Bootstrap 3

要明確中心表單，您可以使用column offsets這樣的，但也有定心幾種不同的方法：

<div class="container"> 
    <div class="row"> 
     <div class="col-md-9 col-md-offset-3 col-sm-10 col-sm-offset-1"> 
      <form style="margin-top:20px"> 
       <div class="row form-group"> 
        <div class="col-md-4"> 
         <label for="exampleInputEmail1">Original Amount</label> 
         <div class="input-group"> 
          <div class="input-group-addon" id="OriginalAmountAddon">$</div> 
          <input type="text" class="form-control" id="exampleInputAmount" placeholder="Amount"> 
         </div> 
        </div> 
        <div class="col-md-4"> 
         <label for="exampleInputEmail1">Billing Amount</label> 
         <div class="input-group"> 
          <div class="input-group-addon" id="BillingAmountAddon">$</div> 
          <input type="text" class="form-control" id="exampleInputAmount" placeholder="Amount"> 
         </div> 
        </div> 
       </div> 
       <div class="row form-group"> 
        <div class="col-md-4"> 
         <label for="exampleInputEmail1">Original Currency Code</label> 
         <div class="input-group"> 
          <div class="input-group-addon" id="OriginalCurrencyAddon">$</div> 
          <select class="form-control" id="OriginalCurrencySelect"> 
           <option value="$">USD</option> 
           <option value="€">EUR</option> 
           <option value="£">GBP</option> 
           <option value="₪">ILS</option> 
          </select> 
         </div> 
        </div> 
        <div class="col-md-4"> 
         <label for="exampleInputEmail1">Billing Currency Code</label> 
         <div class="input-group"> 
          <div class="input-group-addon" id="BillingCurrencyAddon">$</div> 
          <select class="form-control" id="BillingCurrencySelect"> 
           <option value="$">USD</option> 
           <option value="€">EUR</option> 
           <option value="£">GBP</option> 
           <option value="₪">ILS</option> 
          </select> 
         </div> 
        </div> 
       </div> 
      </form> 
     </div> 
    </div> 
</div> 

http://www.codeply.com/go/sRbuCfloDX

Answer 2

當我想這樣做， margin: 0 auto;作品相當好