手风琴我想改变第一个li边界半径和最后一个li边界半径我怎么能帮助我

Question

我想先做li和上一次li border radius 10 px。

我尝试使用css3第一个和最后一个孩子，但它不起作用我不知道为什么。

$(document).ready(function(){

   $('#cssmenu > ul > li ul').each(function(index, element){
  var count = $(element).find('li').length;
  var content = '<span class="cnt">' + count + '</span>';
  $(element).closest('li').children('a').append(content);
});

$('#cssmenu ul ul li:odd').addClass('odd');
$('#cssmenu ul ul li:even').addClass('even');

$('#cssmenu > ul > li > a').click(function() {

  var checkElement = $(this).next();

  $('#cssmenu li').removeClass('active');
  $(this).closest('li').addClass('active'); 

  if((checkElement.is('ul')) && (checkElement.is(':visible'))) {
    $(this).closest('li').removeClass('active');
    checkElement.slideUp('normal');
  }
  if((checkElement.is('ul')) && (!checkElement.is(':visible'))) {
    $('#cssmenu ul ul:visible').slideUp('normal');
    checkElement.slideDown('normal');
  }

  if($(this).closest('li').find('ul').children().length == 0) {
    return true;
  } else {
    return false; 
  }

});// jQuery code goes here!

});

@import url(http://fonts.googleapis.com/css?family=Open+Sans:400,600,300);
#cssmenu,
#cssmenu ul,
#cssmenu li,
#cssmenu a {
  margin: 0;
  padding: 0;
  border: 0;
  list-style: none;
  font-weight: normal;
  text-decoration: none;
  line-height: 1;
  font-family: 'Open Sans', sans-serif;
  font-size: 14px;
  position: relative;
}
#cssmenu a {
  line-height: 1.3;
}


#cssmenu {
  width: 250px;
}
#cssmenu > ul > li > a {
  padding-right: 40px;
  font-size: 25px;
  font-weight: bold;
  display: block;
  background: #bd0e36;
  color: #ffffff;
  border-bottom: 1px solid #5e071b;
  text-transform: uppercase;
  position: relative;
}

#cssmenu > ul > li > a > span {
  background: #ed1144;
  padding: 10px;
  display: block;
  font-size: 13px;
  font-weight: 300;
}
#cssmenu > ul > li > a:hover {
  text-decoration: none;
}
#cssmenu > ul > li.active {
  border-bottom: none;
}
#cssmenu > ul > li.active > a {
  color: #fff;
}
#cssmenu > ul > li.active > a span {
  background: #bd0e36;
}
#cssmenu span.cnt {
  position: absolute;
  top: 8px;
  right: 15px;
  padding: 0;
  margin: 0;
  background: none;
}


#cssmenu ul ul {
  display: none;
}
#cssmenu ul ul li {
  border: 1px solid #e0e0e0;
  border-top: 0;
}
#cssmenu ul ul a {
  padding: 10px;
  display: block;
  color: #ed1144;
  font-size: 13px;
}
#cssmenu ul ul a:hover {
  color: #bd0e36;
}
#cssmenu ul ul li.odd {
  background: #f4f4f4;
}
#cssmenu ul ul li.even {
  background: #fff;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<div id='cssmenu'>
<ul>
   <li><a href='#'><span>Home</span></a></li>
   <li><a href='#'><span>Products</span></a>
      <ul>
         <li><a href='#'><span>Widgets</span></a></li>
         <li><a href='#'><span>Menus</span></a></li>
         <li><a href='#'><span>Products</span></a></li>
      </ul>
   </li>
   <li><a href='#'><span>Company</span></a>
      <ul>
         <li><a href='#'><span>About</span></a></li>
         <li><a href='#'><span>Location</span></a></li>
      </ul>
   </li>
   
</ul>
</div>

Answer 1

将:first-child和:last-child选择器与border-<top/bottom>-<left/right>-radius一起使用。您有一些叠加层，因此您需要在多个元素上应用border-radius，或者在overflow:hidden和li:last-child上使用li:first-child（感谢Danko）。

UPDATE 添加了一些花哨的schmancy border-radius动画。

$(document).ready(function(){

   $('#cssmenu > ul > li ul').each(function(index, element){
  var count = $(element).find('li').length;
  var content = '<span class="cnt">' + count + '</span>';
  $(element).closest('li').children('a').append(content);
});

$('#cssmenu ul ul li:odd').addClass('odd');
$('#cssmenu ul ul li:even').addClass('even');

$('#cssmenu > ul > li > a').click(function() {

  var checkElement = $(this).next();

  $('#cssmenu li').removeClass('active');
  $(this).closest('li').addClass('active'); 

  if((checkElement.is('ul')) && (checkElement.is(':visible'))) {
    $(this).closest('li').removeClass('active');
    checkElement.slideUp('normal');
  }
  if((checkElement.is('ul')) && (!checkElement.is(':visible'))) {
    $('#cssmenu ul ul:visible').slideUp('normal');
    checkElement.slideDown('normal');
  }

  if($(this).closest('li').find('ul').children().length == 0) {
    return true;
  } else {
    return false; 
  }

});// jQuery code goes here!

});

@import url(http://fonts.googleapis.com/css?family=Open+Sans:400,600,300);
#cssmenu,
#cssmenu ul,
#cssmenu li,
#cssmenu a {
  margin: 0;
  padding: 0;
  border: 0;
  list-style: none;
  font-weight: normal;
  text-decoration: none;
  line-height: 1;
  font-family: 'Open Sans', sans-serif;
  font-size: 14px;
  position: relative;
}
#cssmenu a {
  line-height: 1.3;
}


#cssmenu {
  width: 250px;
}
#cssmenu > ul > li > a {
  padding-right: 40px;
  font-size: 25px;
  font-weight: bold;
  display: block;
  background: #bd0e36;
  color: #ffffff;
  border-bottom: 1px solid #5e071b;
  text-transform: uppercase;
  position: relative;
}

#cssmenu > ul > li > a > span {
  background: #ed1144;
  padding: 10px;
  display: block;
  font-size: 13px;
  font-weight: 300;
}
#cssmenu > ul > li > a:hover {
  text-decoration: none;
}
#cssmenu > ul > li.active {
  border-bottom: none;
}
#cssmenu > ul > li.active > a {
  color: #fff;
}
#cssmenu > ul > li.active > a span {
  background: #bd0e36;
}
#cssmenu span.cnt {
  position: absolute;
  top: 8px;
  right: 15px;
  padding: 0;
  margin: 0;
  background: none;
}


#cssmenu ul ul {
  display: none;
}
#cssmenu ul ul li {
  border: 1px solid #e0e0e0;
  border-top: 0;
}
#cssmenu ul ul a {
  padding: 10px;
  display: block;
  color: #ed1144;
  font-size: 13px;
}
#cssmenu ul ul a:hover {
  color: #bd0e36;
}
#cssmenu ul ul li.odd {
  background: #f4f4f4;
}
#cssmenu ul ul li.even {
  background: #fff;
}

#cssmenu ul li:last-child > a {
  transition-property: border-radius;
  transition-duration: 200ms;
}

#cssmenu ul li:last-child > a, #cssmenu ul ul li:last-child {
  border-bottom-left-radius: 10px;
  border-bottom-right-radius: 10px;
}
#cssmenu ul li:first-child > a {
  border-top-left-radius: 10px;
  border-top-right-radius: 10px;
}
#cssmenu ul li:last-child.active > a, #cssmenu ul li:last-child.active > a > span:first-child {
  border-bottom-left-radius: 0;
  border-bottom-right-radius: 0;
}

#cssmenu ul li:last-child > a > span:first-child{
  border-bottom-left-radius: 10px;
}
#cssmenu ul li:first-child > a > span:first-child{
  border-top-left-radius: 10px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<div id='cssmenu'>
<ul>
   <li><a href='#'><span>Home</span></a></li>
   <li><a href='#'><span>Products</span></a>
      <ul>
         <li><a href='#'><span>Widgets</span></a></li>
         <li><a href='#'><span>Menus</span></a></li>
         <li><a href='#'><span>Products</span></a></li>
      </ul>
   </li>
   <li><a href='#'><span>Company</span></a>
      <ul>
         <li><a href='#'><span>About</span></a></li>
         <li><a href='#'><span>Location</span></a></li>
      </ul>
   </li>
   
</ul>
</div>

Answer 2

有两个伪选择器可以让你做到这一点： - -：第一个孩子 {...} - -：最后一个孩子 {...} 如果你正确使用它们，你就可以得到你要求的东西。