模态在页面加载时打开

Question

所以我在我的网站上有一个模态，它打开很好，除了有一个问题之外的一切......它打开一秒然后关闭页面加载。我怎样才能解决这个问题？它由CSS而不是JavaScript提供支持。您按下以打开模态的按钮包含在我的导航栏中。

模态HTML：

<div id="JoinUs" data-toggle="modal" class="modalDialog">
    <div>
        <a href="#close" title="Close" class="close">X</a>
        <h4>Join Us!</h4>

          <input type="text" id="fieldUser" class="input" required pattern=.*\S.* />
          <label for="fieldUser" class="label">Username</label>


          <input type="password" id="fieldPassword" class="input" required pattern=.*\S.* />
          <label for="fieldPassword" class="label">Password</label>

          <button class="btn">Login</button>

    </div>
</div>

模态CSS：

.modalDialog {
    position: fixed;
    font-family: Arial, Helvetica, sans-serif;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    background: rgba(0,0,0,0.8);
    z-index: 99999;
    opacity:0;
    -webkit-transition: opacity 400ms ease-in;
    -moz-transition: opacity 400ms ease-in;
    transition: opacity 400ms ease-in;
    pointer-events: none;
}
.modalDialog:target {
    opacity:1;
    pointer-events: auto;
}

.modalDialog > div {
    width: 400px;
    position: relative;
    margin: 10% auto;
    padding: 5px 20px 13px 20px;
    border-radius: 10px;
    background: #fff;
    background-color: #fff;
}
.close {
    background: #606061;
    color: #FFFFFF;
    line-height: 25px;
    position: absolute;
    right: -12px;
    text-align: center;
    top: -10px;
    width: 24px;
    text-decoration: none;
    font-weight: bold;
    -webkit-border-radius: 12px;
    -moz-border-radius: 12px;
    border-radius: 12px;
    -moz-box-shadow: 1px 1px 3px #000;
    -webkit-box-shadow: 1px 1px 3px #000;
    box-shadow: 1px 1px 3px #000;
}

.close:hover { background:  #2ecc71; }