滚动时隐藏Bootstrap Mobile菜单按钮

Question

我有这个响应式网站，但对于Mobile中的菜单部分，当我滚动它时不再显示按钮，我应该回滚到顶部才能找到按钮。

我不知道为什么移动菜单中的按钮不会在屏幕内滚动。

HTML

    /* ------------------------------------------------------------------------------
	Header
-------------------------------------------------------------------------------*/
#header {
	position: fixed;
	width: 100%;
	z-index: 999;
}
#header .header-content {
	margin: 0 auto;
	max-width: 1170px;
	padding: 20px 0;
	width: 100%;
	-moz-transition: padding 0.3s;
	-o-transition: padding 0.3s;
	-webkit-transition: padding 0.3s;
	transition: padding 0.3s;
}
#header .logo {
	float: right;
	font-size:24px;
	font-weight:700;
	color:#fff;
	text-decoration:none;
	text-transform:uppercase;
	letter-spacing:7px;
}
#header.fixed {
	background-color: #181818;
	padding: 0;
		-moz-transition: background-color 0.3s;
	-o-transition: background-color 0.3s;
	-webkit-transition: background-color 0.3s;
	transition: background-color 0.3s;
}
#header.fixed a {
	color: #fff;
}
#header.fixed .header-content {
	border-bottom: 0;
}
#header.fixed .nav-toggle {
	top: 18px;
	color: #000;
}
.navigation.open {
	opacity: 0.9;
	visibility: visible;
	-moz-transition: opacity 0.5s;
	-o-transition: opacity 0.5s;
	-webkit-transition: opacity 0.5s;
	transition: opacity 0.5s;
}
.navigation {
	float: left;
		padding-top: 20px;
}
.navigation li {
	display: inline-block;
}
.navigation a {
	color: rgba(255, 255, 255, 0.75);
	font-size: 20px;
	margin-left: 40px;
	text-transform: uppercase;
}
.navigation a:hover, .navigation a.active {
	color: #fff;
}
.nav-toggle {
	display: none;
	height: 44px;
	overflow: hidden;
	position: fixed;
	left: 5%;
	text-indent: 100%;
	top: 32px;
	white-space: nowrap;
	width: 44px;
	z-index: 99999;
	-moz-transition: all 0.3s;
	-o-transition: all 0.3s;
	-webkit-transition: all 0.3s;
	transition: all 0.3s;
}
.nav-toggle:before, .nav-toggle:after {
	border-radius: 50%;
	content: "";
	height: 100%;
	left: 0;
	position: absolute;
	top: 0;
	width: 100%;
	-moz-transform: translateZ(0);
	-ms-transform: translateZ(0);
	-webkit-transform: translateZ(0);
	transform: translateZ(0);
	-moz-backface-visibility: hidden;
	-webkit-backface-visibility: hidden;
	backface-visibility: hidden;
	-moz-transition-property: -moz-transform;
	-o-transition-property: -o-transform;
	-webkit-transition-property: -webkit-transform;
	transition-property: transform;
}
.nav-toggle:before {
	background-color: #1192cf;
	-moz-transform: scale(1);
	-ms-transform: scale(1);
	-webkit-transform: scale(1);
	transform: scale(1);
	-moz-transition-duration: 0.3s;
	-o-transition-duration: 0.3s;
	-webkit-transition-duration: 0.3s;
	transition-duration: 0.3s;
}
.nav-toggle:after {
	background-color: #1192cf;
	-moz-transform: scale(0);
	-ms-transform: scale(0);
	-webkit-transform: scale(0);
	transform: scale(0);
	-moz-transition-duration: 0s;
	-o-transition-duration: 0s;
	-webkit-transition-duration: 0s;
	transition-duration: 0s;
}
.nav-toggle span {
	background-color: #fff;
	bottom: auto;
	display: inline-block;
	height: 3px;
	left: 50%;
	position: absolute;
	right: auto;
	top: 50%;
	width: 18px;
	z-index: 10;
	-moz-transform: translateX(-50%) translateY(-50%);
	-ms-transform: translateX(-50%) translateY(-50%);
	-webkit-transform: translateX(-50%) translateY(-50%);
	transform: translateX(-50%) translateY(-50%);
}
.nav-toggle span:before, .nav-toggle span:after {
	background-color: #fff;
	content: "";
	height: 100%;
	position: absolute;
	right: 0;
	top: 0;
	width: 100%;
	-moz-transform: translateZ(0);
	-ms-transform: translateZ(0);
	-webkit-transform: translateZ(0);
	transform: translateZ(0);
	-moz-backface-visibility: hidden;
	-webkit-backface-visibility: hidden;
	backface-visibility: hidden;
	-moz-transition: -moz-transform 0.3s;
	-o-transition: -o-transform 0.3s;
	-webkit-transition: -webkit-transform 0.3s;
	transition: transform 0.3s;
}
.nav-toggle span:before {
	-moz-transform: translateY(-6px) rotate(0deg);
	-ms-transform: translateY(-6px) rotate(0deg);
	-webkit-transform: translateY(-6px) rotate(0deg);
	transform: translateY(-6px) rotate(0deg);
}
.nav-toggle span:after {
	-moz-transform: translateY(6px) rotate(0deg);
	-ms-transform: translateY(6px) rotate(0deg);
	-webkit-transform: translateY(6px) rotate(0deg);
	transform: translateY(6px) rotate(0deg);
}
.nav-toggle.close-nav:before {
	-moz-transform: scale(0);
	-ms-transform: scale(0);
	-webkit-transform: scale(0);
	transform: scale(0);
}
.nav-toggle.close-nav:after {
	-moz-transform: scale(1);
	-ms-transform: scale(1);
	-webkit-transform: scale(1);
	transform: scale(1);
}
.nav-toggle.close-nav span {
	background-color: rgba(255, 255, 255, 0);
}
.nav-toggle.close-nav span:before, .nav-toggle.close-nav span:after {
	background-color: #fff;
}
.nav-toggle.close-nav span:before {
	-moz-transform: translateY(0) rotate(45deg);
	-ms-transform: translateY(0) rotate(45deg);
	-webkit-transform: translateY(0) rotate(45deg);
	transform: translateY(0) rotate(45deg);
}
.nav-toggle.close-nav span:after {
	-moz-transform: translateY(0) rotate(-45deg);
	-ms-transform: translateY(0) rotate(-45deg);
	-webkit-transform: translateY(0) rotate(-45deg);
	transform: translateY(0) rotate(-45deg);
}

@media screen and (max-width: 1024px) {
 #header .header-content {
 width: 90%;
 padding:20px 0px;
}
 #header.fixed a {
 color: #000;
}
 .nav-toggle {
 display: block;
}
 .navigation {
 position: fixed;
 background-color: #000;
 width: 100%;
 height: 100%;
 top: 0;
 left: 0;
 z-index: 99999;
 visibility: hidden;
 opacity: 0;
 -webkit-transition: opacity 0.5s, visibility 0s 0.5s;
 transition: opacity 0.5s, visibility 0s 0.5s;
}
 .navigation .primary-nav {
 position: relative;
 top: 45%;
 -moz-transform: translateY(-45%);
 -ms-transform: translateY(-45%);
 -webkit-transform: translateY(-45%);
 transform: translateY(-45%);
}
 .navigation li {
 display: block;
 margin-bottom: 20px;
}
 .navigation a {
 display: block;
 font-size: 25px;
 margin: 0;
 text-align: center;
}
 .flex-control-nav {
 bottom: 20px;
}
}

   <header id="header">
    <div class="header-content clearfix"> <a class="logo" href="index.html"><img style="logo-size" src="images/logo-awaed.png" width="150px" height="62px"></a>
      <nav class="navigation" role="navigation">
        <ul class="primary-nav">
          <li><a href="#intro">عن الشركة</a></li>
          <li><a href="#services">خدماتنا</a></li>
          <li><a href="#contact">اتصل بنا</a></li>
        </ul>
      </nav>
      <a href="#" class="nav-toggle">Menu<span></span></a> </div>
  </header>