标头未在IE中正确定位

Question

正在处理标头，当前正在使用Flexbox放置标头，并且一切都正确地居中放置，就像我在Mac上进行本地测试时所希望的那样，但是当我团队中的其他人在基于IE或Windows的计算机上进行测试时，标头不再位于中央。它变成全宽，位于左侧或右侧，我真的不确定我丢失了什么或做错了什么。任何帮助将不胜感激。

应该是什么样子

在Windows机器上它正在做什么

html

$('#option1').parent()

css

<header class="mcc-header ember-view">
<div class="mcc-full mcc-div">
    <div class="mcc-header-content">
    <a href="/" class="mcc-header-logo">
        <span class="mcc-logo-title">MCC Semi</span>
    </a>

    <ul class="mcc-header-nav">
        <li class="mcc-header-nav-item">
            <a href="" class="mcc-header-nav-link guide">Company Profile</a>
        </li>
        <li class="mcc-header-nav-item">
            <a href="" class="mcc-header-nav-link guide">News</a>
        </li>
        <li class="mcc-header-nav-item">
            <a href="" class="mcc-header-nav-link guide">Contact Us</a>
        </li>
        <li class="mcc-header-nav-item">
            <a href="" class="mcc-header-nav-link guide">EN | CN</a>
        </li>
        <li class="mcc-header-nav-item">
            <a href="" class="mcc-header-nav-link guide"></a>
        </li>
        <li class="mcc-header-nav-item">
            <a href="" class="mcc-header-nav-link guide">Login</a>
        </li>
        <li class="mcc-header-nav-item">
            <a href="" class="mcc-header-nav-link guide">Sign Up</a>
        </li>
    </ul>

    </div>
</div>
<div class="mcc-full">
    <div id="main-menu" class="mcc-header-menu">
        <div class="mcc-full">
    <div class="mcc-header-legal">
        <ul class="mcc-header-legal-list">
            <li class="mcc-header-legal-item">
                <a href="" class="guide">Products</a>
            </li>
            <li class="mcc-header-legal-item">
                <a href="" class="guide">Catalog</a>
            </li>
            <li class="mcc-header-legal-item">
                <a href="" class="guide">Applications</a>
            </li>
            <li class="mcc-header-legal-item">
                <a href="" class="guide">Quality</a>
            </li>
            <li class="mcc-header-legal-item">
                <a href="" class="guide">Calendar</a>
            </li>
        </ul>
    </div>
</div>
        <form class="mcchf" id="mcchf-h-search" action="" method="get" title="" role="search">
            <label class="mcchf">Search</label>
            <input class="mcchf" id="mcchf-h-st" type="text" name="q" placeholder="Search">
            <label class="mcchf">Submit search query</label>
            <input class="mcchf" id="mcchf-h-sb" type="submit" value="">
        </form>
    </div>
</div>
</div>
</header>