Css 为什么我的悬停背景会延伸到容器之外

我对CSS比较陌生，并尝试创建一个CSS下拉菜单

经过几个小时的css阅读，我已经创建了一个，但在悬停时，父UL上的最后一个孩子会流血

以下是JSFIDLE链接：

---

我为我卑鄙的css道歉

这是因为

.mini nav ul li

是

position:relative;
margin-right:-4px;

---

您已经使它正确运行了4个像素，这就把它扔掉了。

在您的Css上，找到以下代码

mini-nav ul > li:last-child { border-right: none; }

并在其中添加“边距：0”，如下所示：

mini-nav ul > li:last-child { border-right: none; margin:0; }

最后，这就是你想要的

链接断开时的工作代码：

    /* Parent CSS */
mini-nav ul {
    width: 237px;
    text-align: center;
    display: inline;
    margin: 0;
    padding: 5px 0 5px 0px;
    list-style-type: none;
    -moz-border-radius: 5px;
    -webkit-border-radius: 5px;
    border-radius: 5px;
    background: #58585A;
    box-shadow: 3px 3px 5px #828282;
}
mini-nav ul li {
    font-size: 13px;
    display: inline-block;
    margin-right:-4px;
    position: relative;
    width: 78px;
    padding: 5px 0 5px 0px;
    border-right: 1px solid white;
    cursor: pointer;
    -webkit-transition: all 0.2s;
    -moz-transition: all 0.2s;
    -ms-transition: all 0.2s;
    -o-transition: all 0.2s;
    transition: all 0.2s;
}
mini-nav ul > li:last-child { border-right: none; margin:0; }
mini-nav ul li:hover 
{
    background: #E8E8E8; 
    color: black; 
    background-image: url(../mes-images/menu-topper.png);
    background-position: top left;
    background-repeat: repeat-x;
    display: inline-block;
}

mini-nav ul li:hover:first-child {
    -moz-border-radius: 5px 0 0 0;
    -webkit-border-radius: 5px 0 0 0;
    border-radius: 5px 0 0 0;
    -webkit-background-clip: padding-box; 
    -moz-background-clip:    padding; 
    background-clip:         padding-box;
}
mini-nav ul li:hover:last-child {
    -moz-border-radius: 0 5px 0 0;
    -webkit-border-radius: 0 5px 0 0;
    border-radius: 0 5px 0 0;
    -webkit-background-clip: padding-box; 
    -moz-background-clip:    padding; 
    background-clip:         padding-box;
}

mini-nav ul li:hover a { color: black; }

mini-nav ul li:hover ul {
  display: block;
  opacity: 0.8;
  visibility: visible;
}

mini-nav ul li a { color: White; text-decoration: none; }

/* Child CSS */
mini-nav ul li ul {
    text-align: left;
    padding:0;
    position: absolute;
    top: 27px;
    left: 0;
    width: auto;
    display: none;
    visibility: hidden;
    -webkit-transiton: opacity 0.2s;
    -moz-transition: opacity 0.2s;
    -ms-transition: opacity 0.2s;
    -o-transition: opacity 0.2s;
    -transition: opacity 0.2s;
    -moz-border-radius: 0 0 5px 5px;
    -webkit-border-radius: 0 0 5px 5px;
    border-radius: 0 0 5px 5px;
}
mini-nav ul ul > li:last-child { border-bottom: none; }
mini-nav ul li ul li:hover {
    background: #E8E8E8; 
    color: black;
    width: 110px;
}
mini-nav ul li ul li {  
  display: block; 
  color: #fff;
  width: 110px;
  border-bottom: solid 1px silver;
  padding-left: 12px;
  border-right: none;
  margin-right: 0;
}
mini-nav ul li ul li:hover:last-child {
    -moz-border-radius: 0 0 5px 5px;
    -webkit-border-radius: 0 0 5px 5px;
    border-radius: 0 0 5px 5px;
}

---

中心子菜单的问题是否超出了主菜单的范围。。。但我确实注意到了这一点，并添加了以下代码来修复它：mini nav ul li:last child ul{left:-44px；}如果您认为这个答案是正确的，请毫不犹豫地接受：）

mini-nav ul > li:last-child { border-right: none; margin:0; }

    /* Parent CSS */
mini-nav ul {
    width: 237px;
    text-align: center;
    display: inline;
    margin: 0;
    padding: 5px 0 5px 0px;
    list-style-type: none;
    -moz-border-radius: 5px;
    -webkit-border-radius: 5px;
    border-radius: 5px;
    background: #58585A;
    box-shadow: 3px 3px 5px #828282;
}
mini-nav ul li {
    font-size: 13px;
    display: inline-block;
    margin-right:-4px;
    position: relative;
    width: 78px;
    padding: 5px 0 5px 0px;
    border-right: 1px solid white;
    cursor: pointer;
    -webkit-transition: all 0.2s;
    -moz-transition: all 0.2s;
    -ms-transition: all 0.2s;
    -o-transition: all 0.2s;
    transition: all 0.2s;
}
mini-nav ul > li:last-child { border-right: none; margin:0; }
mini-nav ul li:hover 
{
    background: #E8E8E8; 
    color: black; 
    background-image: url(../mes-images/menu-topper.png);
    background-position: top left;
    background-repeat: repeat-x;
    display: inline-block;
}

mini-nav ul li:hover:first-child {
    -moz-border-radius: 5px 0 0 0;
    -webkit-border-radius: 5px 0 0 0;
    border-radius: 5px 0 0 0;
    -webkit-background-clip: padding-box; 
    -moz-background-clip:    padding; 
    background-clip:         padding-box;
}
mini-nav ul li:hover:last-child {
    -moz-border-radius: 0 5px 0 0;
    -webkit-border-radius: 0 5px 0 0;
    border-radius: 0 5px 0 0;
    -webkit-background-clip: padding-box; 
    -moz-background-clip:    padding; 
    background-clip:         padding-box;
}

mini-nav ul li:hover a { color: black; }

mini-nav ul li:hover ul {
  display: block;
  opacity: 0.8;
  visibility: visible;
}

mini-nav ul li a { color: White; text-decoration: none; }

/* Child CSS */
mini-nav ul li ul {
    text-align: left;
    padding:0;
    position: absolute;
    top: 27px;
    left: 0;
    width: auto;
    display: none;
    visibility: hidden;
    -webkit-transiton: opacity 0.2s;
    -moz-transition: opacity 0.2s;
    -ms-transition: opacity 0.2s;
    -o-transition: opacity 0.2s;
    -transition: opacity 0.2s;
    -moz-border-radius: 0 0 5px 5px;
    -webkit-border-radius: 0 0 5px 5px;
    border-radius: 0 0 5px 5px;
}
mini-nav ul ul > li:last-child { border-bottom: none; }
mini-nav ul li ul li:hover {
    background: #E8E8E8; 
    color: black;
    width: 110px;
}
mini-nav ul li ul li {  
  display: block; 
  color: #fff;
  width: 110px;
  border-bottom: solid 1px silver;
  padding-left: 12px;
  border-right: none;
  margin-right: 0;
}
mini-nav ul li ul li:hover:last-child {
    -moz-border-radius: 0 0 5px 5px;
    -webkit-border-radius: 0 0 5px 5px;
    border-radius: 0 0 5px 5px;
}