使用materializecss时，navbar无法正确调整大小

Question

我在http://materializecss.com/navbar.html上的示例，我的代码是这样的：

<div class="navbar-fixed">
                    <nav>
                        <div class="nav-wrapper">
                            <a href="#!" class="brand-logo center">Logo</a>
                            <a href="#" data-activates="mobile-demo" class="button-collapse"><i class="material-icons">menu</i></a>
                            <ul class="left">
                                <li><a href="sass.html">About Us</a></li>
                                <li><a href="badges.html">Services</a></li>
                            </ul>
                            <ul class="right">
                                <li><a href="sass.html">Testimonials</a></li>
                                <li><a href="badges.html">Contact Us</a></li>
                            </ul>

                            <ul class="side-nav" id="mobile-demo">
                                <li><a href="sass.html">Sass</a></li>
                                <li><a href="badges.html">Components</a></li>
                                <li><a href="collapsible.html">Javascript</a></li>
                                <li><a href="mobile.html">Mobile</a></li>
                            </ul>
                        </div>
                    </nav>
                </div>

 看起来像这样： 但是当窗口/网页变小时，导航内容会混乱，如下所示： 我能做错什么？请帮忙

Answer 1

<div class="navbar-fixed">
<nav>
    <div class="nav-wrapper">
        <a href="#!" class="brand-logo center">Logo</a>
        <a href="#" data-activates="mobile-demo" class="button-collapse"><i class="material-icons">menu</i></a>
        <ul class="left hide-on-med-and-down">
            <li><a href="sass.html">About Us</a></li>
            <li><a href="badges.html">Services</a></li>
        </ul>
        <ul class="right hide-on-med-and-down">
            <li><a href="sass.html">Testimonials</a></li>
            <li><a href="badges.html">Contact Us</a></li>
        </ul>

        <ul class="side-nav" id="mobile-demo">
            <li><a href="sass.html">Sass</a></li>
            <li><a href="badges.html">Components</a></li>
            <li><a href="collapsible.html">Javascript</a></li>
            <li><a href="mobile.html">Mobile</a></li>
        </ul>
    </div>
</nav>

Answer 2

<nav>
<div class="nav-wrapper">
  <a href="#!" class="brand-logo">Logo</a>
  <a href="#" data-activates="mobile-demo" class="button-collapse"><i class="material-icons">menu</i></a>
  <ul class="right hide-on-med-and-down">
    <li><a href="sass.html">Sass</a></li>
    <li><a href="badges.html">Components</a></li>
    <li><a href="collapsible.html">Javascript</a></li>
    <li><a href="mobile.html">Mobile</a></li>
  </ul>
  <ul class="side-nav" id="mobile-demo">
    <li><a href="sass.html">Sass</a></li>
    <li><a href="badges.html">Components</a></li>
    <li><a href="collapsible.html">Javascript</a></li>
    <li><a href="mobile.html">Mobile</a></li>
  </ul>
</div>