菜单打开时如何在主体（背景）中禁用滚动？

Question

当我打开主菜单时，我基本上是在尝试禁用主体滚动。我希望有一个没有 JS 的解决方案，因为我不太熟悉它，但不介意一些帮助。

这是我的代码笔，仅使用 CSS。如您所见，当菜单打开时，后台的正文仍然可以滚动。我需要禁用该滚动，但仍然能够在菜单本身内滚动。 提前致谢！

Codepen

/* Screen reader only */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  border: 0;
}

/* Button styling */
.menu-toggle {
  display: inline-block;
  padding: .75em 15px;
  line-height: 1em;
  font-size: 1em;
  color: #333;
}

.menu-toggle:hover,
.menu-toggle:focus {
  color: #c00;
}

/*
 Default styles + Mobile first
 Offscreen menu style
*/
.main-menu {
  position: absolute;
  display: none;
  left: -200px;
  top: 0;
  height: 100%;
    overflow-y: scroll;
    overflow-x: visible;
    transition: left 0.3s ease,
                      box-shadow 0.3s ease;
    z-index: 999;
}

.main-menu ul {
  list-style: none;
  margin: 0;
  padding: 2.5em 0 0;
  /* Hide shadow w/ -8px while 'closed' */
  -webkit-box-shadow: -8px 0 8px rgba(0,0,0,.5);
     -moz-box-shadow: -8px 0 8px rgba(0,0,0,.5);
          box-shadow: -8px 0 8px rgba(0,0,0,.5);
  min-height: 100%;
  width: 200px;
  background: #1a1a1a;
}

.main-menu a {
  display: block;
  padding: .75em 15px;
  line-height: 1em;
  font-size: 1em;
  color: #fff;
  text-decoration: none;
  border-bottom: 1px solid #383838;
}

.main-menu li:first-child a {
  border-top: 1px solid #383838;
}

.main-menu a:hover,
.main-menu a:focus {
  background: #333;
  text-decoration: underline;
}

.main-menu .menu-close {
  position: absolute;
  right: 0;
  top: 0;
}

/*
 On small devices, allow it to toggle...
*/
/*
 :target for non-JavaScript
 [aria-expanded] will be used if/when JavaScript is added to improve interaction, though it's completely optional.
*/
.main-menu:target,
.main-menu[aria-expanded="true"] {
  display: block;
  left: 0;
  outline: none;
  -moz-box-shadow: 3px 0 12px rgba(0,0,0,.25);
  -webkit-box-shadow: 3px 0 12px rgba(0,0,0,.25);
  box-shadow: 3px 0 12px rgba(0,0,0,.25);
}

.main-menu:target .menu-close,
.main-menu[aria-expanded="true"] .menu-close {
  z-index: 1001;
}

.main-menu:target ul,
.main-menu[aria-expanded="true"] ul {
  position: relative;
  z-index: 1000;
}

/* 
 We could us `.main-menu:target:after`, but
 it wouldn't be clickable.
*/
.main-menu:target + .backdrop,
.main-menu[aria-expanded="true"] + .backdrop{
  position: absolute;
  display: block;  
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  z-index: 998;
  background: #000;
  background: rgba(0,0,0,.85);
  cursor: default;
}

@supports (position: fixed) {
  .main-menu,
  .main-menu:target + .backdrop,
  .main-menu[aria-expanded="true"] + .backdrop{
    position: fixed;
  }
}

/*
 Larger screen styling
 Horizontal menu
*/
{
  .menu-toggle,
  .main-menu .menu-close {
    display: none;
  }
  
  /* Undo positioning of off-canvas menu */
  .main-menu {
    position: relative;
        left: auto;
        top: auto;
        height: auto;
    display: block;
  }
  
  .main-menu ul {
    display: flex;
    
    /* Undo off-canvas styling */
    padding: 0;
    -webkit-box-shadow: none;
       -moz-box-shadow: none;
            box-shadow: none;
    height: auto;
    width: auto;
    background: none;
  }
  
  .main-menu a {
    color: #06c;
    border: 0 !important; /* Remove borders from off-canvas styling */
  }
  
  .main-menu a:hover,
  .main-menu a:focus {
    background: none; /* Remove background from off-canvas styling */
    color: #c00;
  }
}

<a href="#main-menu"
     id="main-menu-toggle"
     class="menu-toggle"
     aria-label="Open main menu">
    <span class="sr-only">Open main menu</span>
    <svg xmlns="http://www.w3.org/2000/svg" height="24px" viewBox="0 0 24 24" width="24px" ><path fill="#999999" d="M3 18h18v-2H3v2zm0-5h18v-2H3v2zm0-7v2h18V6H3z"/></svg>
  </a>
  
  
  <nav id="main-menu" class="main-menu" aria-label="Main menu">
    <a href="#main-menu-toggle"
       id="main-menu-close"
       class="menu-close"
       aria-label="Close main menu">
      <span class="sr-only">Close main menu</span>
      <svg xmlns="http://www.w3.org/2000/svg" height="24px" viewBox="0 0 24 24" width="24px" ><path fill="#999999" d="M19 6.41L17.59 5 12 10.59 6.41 5 5 6.41 10.59 12 5 17.59 6.41 19 12 13.41 17.59 19 19 17.59 13.41 12z"/></svg>
    </a>
    <ul>
      <li><a href="#">Products</a></li>
      <li><a href="#">About</a></li>
      <li><a href="#">Contact</a></li>
    </ul>
  </nav>
  <a href="#main-menu-toggle"
     class="backdrop"
     tabindex="-1"
     aria-hidden="true" hidden></a>

<p>
  "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
 "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
</p>

<p>
  "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
 "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
</p>

<p>
  "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
 "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
</p>

<p>
  "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
 "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
</p>

<p>
  "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
 "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
</p>

Answer 1

我使用 JS。当菜单打开/关闭时，只需在 html 标签上切换一个“noscroll”类。

  document.querySelector('html').classList.add('noscroll');
  document.querySelector('html').classList.remove('noscroll');

html.noscroll {
    overflow: hidden;
}
html.noscroll body {
    overflow: hidden;
}

Answer 2

这是一种无需 js 的 hack 方法。我所做的是为你的整个内容制作了一个容器 div 并给它一个类 .contentWrap 然后我将此代码添加到你的 CSS 中：

.main-menu:target ~ .contentWrap{ 
height: 80vh; overflow: hidden;
}

它的作用是让你的整个内容的高度尽量在 80vh 以内，然后将溢出设置为隐藏，这样它就会移除滚动条。

这又是一种 hack 方式，因此滚动可能适用于某些形状怪异的屏幕尺寸（例如 Stack Overflow 上的代码预览），但应该适用于大多数屏幕尺寸。

检查一下：

https://jsfiddle.net/0mcpon8a/

/* Screen reader only */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  border: 0;
}

/* Button styling */
.menu-toggle {
  display: inline-block;
  padding: .75em 15px;
  line-height: 1em;
  font-size: 1em;
  color: #333;
}

.menu-toggle:hover,
.menu-toggle:focus {
  color: #c00;
}

/*
 Default styles + Mobile first
 Offscreen menu style
*/
.main-menu {
  position: absolute;
  display: none;
  left: -200px;
  top: 0;
  height: 100%;
    overflow-y: scroll;
    overflow-x: visible;
    transition: left 0.3s ease,
                      box-shadow 0.3s ease;
    z-index: 999;
}

.main-menu ul {
  list-style: none;
  margin: 0;
  padding: 2.5em 0 0;
  /* Hide shadow w/ -8px while 'closed' */
  -webkit-box-shadow: -8px 0 8px rgba(0,0,0,.5);
     -moz-box-shadow: -8px 0 8px rgba(0,0,0,.5);
          box-shadow: -8px 0 8px rgba(0,0,0,.5);
  min-height: 100%;
  width: 200px;
  background: #1a1a1a;
}

.main-menu a {
  display: block;
  padding: .75em 15px;
  line-height: 1em;
  font-size: 1em;
  color: #fff;
  text-decoration: none;
  border-bottom: 1px solid #383838;
}

.main-menu li:first-child a {
  border-top: 1px solid #383838;
}

.main-menu a:hover,
.main-menu a:focus {
  background: #333;
  text-decoration: underline;
}

.main-menu .menu-close {
  position: absolute;
  right: 0;
  top: 0;
}

/*
 On small devices, allow it to toggle...
*/
/*
 :target for non-JavaScript
 [aria-expanded] will be used if/when JavaScript is added to improve interaction, though it's completely optional.
*/
.main-menu:target,
.main-menu[aria-expanded="true"] {
  display: block;
  left: 0;
  outline: none;
  -moz-box-shadow: 3px 0 12px rgba(0,0,0,.25);
  -webkit-box-shadow: 3px 0 12px rgba(0,0,0,.25);
  box-shadow: 3px 0 12px rgba(0,0,0,.25);
}

.main-menu:target .menu-close,
.main-menu[aria-expanded="true"] .menu-close {
  z-index: 1001;
}

.main-menu:target ul,
.main-menu[aria-expanded="true"] ul {
  position: relative;
  z-index: 1000;
}

/* 
 We could us `.main-menu:target:after`, but
 it wouldn't be clickable.
*/
.main-menu:target + .backdrop,
.main-menu[aria-expanded="true"] + .backdrop{
  position: absolute;
  display: block;  
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  z-index: 998;
  background: #000;
  background: rgba(0,0,0,.85);
  cursor: default;
}

@supports (position: fixed) {
  .main-menu,
  .main-menu:target + .backdrop,
  .main-menu[aria-expanded="true"] + .backdrop{
    position: fixed;
  }
}

/*
 Larger screen styling
 Horizontal menu
*/
{
  .menu-toggle,
  .main-menu .menu-close {
    display: none;
  }
  
  /* Undo positioning of off-canvas menu */
  .main-menu {
    position: relative;
        left: auto;
        top: auto;
        height: auto;
    display: block;
  }
  
  .main-menu ul {
    display: flex;
    
    /* Undo off-canvas styling */
    padding: 0;
    -webkit-box-shadow: none;
       -moz-box-shadow: none;
            box-shadow: none;
    height: auto;
    width: auto;
    background: none;
  }
  
  .main-menu a {
    color: #06c;
    border: 0 !important; /* Remove borders from off-canvas styling */
  }
  
  .main-menu a:hover,
  .main-menu a:focus {
    background: none; /* Remove background from off-canvas styling */
    color: #c00;
  }
}


.main-menu:target ~ .contentWrap{ 
height: 80vh; overflow: hidden;
}

<a href="#main-menu"
     id="main-menu-toggle"
     class="menu-toggle"
     aria-label="Open main menu">
    <span class="sr-only">Open main menu</span>
    <svg xmlns="http://www.w3.org/2000/svg" height="24px" viewBox="0 0 24 24" width="24px" ><path fill="#999999" d="M3 18h18v-2H3v2zm0-5h18v-2H3v2zm0-7v2h18V6H3z"/></svg> 
  </a>
  
  
  <nav id="main-menu" class="main-menu" aria-label="Main menu">
    <a href="#main-menu-toggle"
       id="main-menu-close"
       class="menu-close"
       aria-label="Close main menu">
      <span class="sr-only">Close main menu</span>
      <svg xmlns="http://www.w3.org/2000/svg" height="24px" viewBox="0 0 24 24" width="24px" ><path fill="#999999" d="M19 6.41L17.59 5 12 10.59 6.41 5 5 6.41 10.59 12 5 17.59 6.41 19 12 13.41 17.59 19 19 17.59 13.41 12z"/></svg>
    </a>
    <ul>
      <li><a href="#">Products</a></li>
      <li><a href="#">About</a></li>
      <li><a href="#">Contact</a></li>
    </ul>
  </nav>
  <a href="#main-menu-toggle"
     class="backdrop"
     tabindex="-1"
     aria-hidden="true" hidden></a>

<div class="contentWrap">
<p>
  "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
 "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
</p>

<p>
  "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
 "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
</p>

<p>
  "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
 "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
</p>

<p>
  "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
 "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
</p>

<p>
  "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
 "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  
</p>
</div>