菜单和子菜单之间的 CSS 闪烁

Question

将鼠标悬停在菜单上向下移动到子菜单时，我的子菜单会跳动和闪烁。

似乎有一些我找不到的空白或者这是我的 CSS 的另一个问题。我正在尝试使菜单尽可能流畅，不会闪烁。

#cssmenu,
#cssmenu ul,
#cssmenu li,
#cssmenu a {
  border: none;
  line-height: 1;
  margin: 0;
  padding: 0;
}
#cssmenu {
  height: 37px;
  display: block;
  border: 1px solid;
  border-radius: 5px;
  width: auto;
  border-color: #336699;
  margin: 0;
  padding: 0;
}
#cssmenu > ul {
  list-style: inside none;
  margin: 0;
  padding: 0;
}
#cssmenu > ul > li {
  list-style: inside none;
  float: left;
  display: inline-block;
  position: relative;
  margin: 0;
  padding: 0;
}
#cssmenu.align-center > ul {
  text-align: center;
}
#cssmenu.align-center > ul > li {
  float: none;
  margin-left: -3px;
}
#cssmenu.align-center ul ul {
  text-align: left;
}
#cssmenu.align-center > ul > li:first-child > a {
  border-radius: 0;
}
#cssmenu > ul > li > a {
  outline: none;
  display: block;
  position: relative;
  text-align: center;
  text-decoration: none;
  text-shadow: 1px 1px 0 rgba(55, 110, 166, 0.6);
  font-weight: 700;
  font-size: 13px;
  font-family: verdana;
  border-right: 1px solid #336699;
  color: #ffffff;
  padding: 12px 20px;
}
#cssmenu > ul > li:first-child > a {
  border-radius: 5px 0 0 5px;
}
#cssmenu > ul > li > a:after {
  content: "";
  position: absolute;
  border-right: 1px solid;
  top: -1px;
  bottom: -1px;
  right: -2px;
  z-index: 99;
  border-color: #3c3c3c;
}
#cssmenu ul li.has-sub:hover > a:after {
  top: 0;
  bottom: 0;
}
#cssmenu > ul > li.has-sub > a:before {
  content: "";
  position: absolute;
  top: 18px;
  right: 6px;
  border: 5px solid transparent;
  border-top: 5px solid #ffffff;
}
#cssmenu > ul > li.has-sub:hover > a:before {
  top: 19px;
}
#cssmenu > ul > li.has-sub:hover > a {
  /*padding-bottom: 14px;*/
  z-index: 999;
  border-color: #2B5681;
}
#cssmenu ul li.has-sub:hover > ul,
#cssmenu ul li.has-sub:hover > div {
  display: block;
}
#cssmenu > ul > li.has-sub > a:hover,
#cssmenu > ul > li.has-sub:hover > a {
  background: #2B5681;
  border-color: #2B5681;
}
#cssmenu ul li > ul,
#cssmenu ul li > div {
  display: none;
  width: auto;
  position: absolute;
  top: 38px;
  background: #2B5681;
  border-radius: 0 0 5px 5px;
  z-index: 999;
  padding: 10px 0;
}
#cssmenu ul li > ul {
  width: 200px;
}
#cssmenu ul ul ul {
  position: absolute;
}
#cssmenu ul ul li:hover > ul {
  left: 100%;
  top: -10px;
  border-radius: 5px;
}
#cssmenu ul li > ul li {
  display: block;
  list-style: inside none;
  position: relative;
  margin: 0;
  padding: 0;
}
#cssmenu ul li > ul li a {
  outline: none;
  display: block;
  position: relative;
  font: 10pt verdana;
  color: #ffffff;
  text-decoration: none;
  text-shadow: 1px 1px 0 rgba(55, 110, 166, 0.6);
  margin: 0;
  padding: 8px 20px;
}
#cssmenu,
#cssmenu ul ul > li:hover > a,
#cssmenu ul ul li a:hover {
  background: #2B5681;
  background: -moz-linear-gradient(top, #2B5681 0%, #336699 100%);
  background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #2B5681), color-stop(100%, #336699));
  background: -webkit-linear-gradient(top, #2B5681 0%, #336699 100%);
  background: -o-linear-gradient(top, #2B5681 0%, #336699 100%);
  background: -ms-linear-gradient(top, #2B5681 0%, #336699 100%);
  background: linear-gradient(top, #2B5681 0%, #336699 100%);
}
#cssmenu > ul > li > a:hover {
  background: #336699;
  color: Orange;
}
#cssmenu ul ul a:hover {
  color: orange;
  font-weight: bold;
}
#cssmenu > ul > li.has-sub > a:hover:before {
  border-top: 5px solid Orange;
}

<div id='cssmenu'>
  <ul style="display: table;">
    <li style="width: 108px;" class='active'><a runat="server" href='~/Applications/Sentinel/Default.aspx'><span>Home</span></a>
    </li>
    <li style="width: 118px;" class='has-sub'><a><span>Jobs</span></a>
      <ul>
        <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/Jobs.aspx'>Jobs List<span></span></a>
        </li>
        <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/AddJob.aspx'><span>Add New Job</span></a>
        </li>
      </ul>
    </li>
    <li style="width: 118px;" class='has-sub'><a><span>Quotes</span></a>
      <ul>
        <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/AddQuote.aspx'>Raise New Quote<span></span></a>
        </li>
        <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/ViewQuotes.aspx'><span>View Quotes</span></a>
        </li>
        <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/UploadQuote.aspx'><span>Upload New Quote</span></a>
        </li>
      </ul>
    </li>
    <li style="width: 108px;"><a runat="server" href='~/Applications/Sentinel/Locations.aspx'><span>Locations</span></a>
    </li>
    <li style="width: 108px;"><a runat="server" href='~/Applications/Sentinel/Assets.aspx'><span>Assets</span></a>
    </li>
    <li style="width: 118px;" class='has-sub'><a><span>Admin</span></a>
      <ul>
        <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/Administration/ContractorsAdmin.aspx'>Contractors<span></span></a>
        </li>
        <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/Administration/CreateNewUser.aspx'><span>Create New User Account</span></a>
        </li>
        <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/Administration/JobStatusAdmin.aspx'><span>Job Status Admin</span></a>
        </li>
        <li class='has-sub'><a runat="server" href='~/Applications/Sentinel/Administration/JobTypesAdmin.aspx' style="text-align: left;"><span>Job Types Admin</span></a>
        </li>
        <li class="has-sub"><a runat="server" href='~/Applications/Sentinel/Administration/ProjectAdmin.aspx' style="text-align: left;"><span>Project Admin</span></a>
        </li>
        <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/Administration/UserAdmin.aspx'><span>User Admin</span></a>
        </li>
      </ul>
    </li>
    <li><a runat="server" style="width: 108px;"><span>Reports</span></a>
    </li>

    <li class='last' style="width: 125px;"><a runat="server" href='~/LoggedOut.aspx'><span>Log Out</span></a>
    </li>
  </ul>
</div>

Answer 1

使顶部:18px；在 #cssmenu > ul > li.has-sub:hover > a:before 中注释 font-weight: bold;在#cssmenu ul ul a:hover

   #cssmenu,
    #cssmenu ul,
    #cssmenu li,
    #cssmenu a {
        border: none;
        line-height: 1;
        margin: 0;
        padding: 0;
    }

    #cssmenu {
        height: 37px;
        display: block;
        border: 1px solid;
        border-radius: 5px;
        width: auto;
        border-color: #336699;
        margin: 0;
        padding: 0;
    }

        #cssmenu > ul {
            list-style: inside none;
            margin: 0;
            padding: 0;
        }

            #cssmenu > ul > li {
                list-style: inside none;
                float: left;
                display: inline-block;
                position: relative;
                margin: 0;
                padding: 0;
            }

        #cssmenu.align-center > ul {
            text-align: center;
        }

            #cssmenu.align-center > ul > li {
                float: none;
                margin-left: -3px;
            }

        #cssmenu.align-center ul ul {
            text-align: left;
        }

        #cssmenu.align-center > ul > li:first-child > a {
            border-radius: 0;
        }

        #cssmenu > ul > li > a {
            outline: none;
            display: block;
            position: relative;
            text-align: center;
            text-decoration: none;
            text-shadow: 1px 1px 0 rgba(55, 110, 166, 0.6);
            font-weight: 700;
            font-size: 13px;
            font-family: verdana;
            border-right: 1px solid #336699;
            color: #ffffff;
            padding: 12px 20px;
        }

        #cssmenu > ul > li:first-child > a {
            border-radius: 5px 0 0 5px;
        }

        #cssmenu > ul > li > a:after {
            content: "";
            position: absolute;
            border-right: 1px solid;
            top: -1px;
            bottom: -1px;
            right: -2px;
            z-index: 99;
            border-color: #3c3c3c;
        }

        #cssmenu ul li.has-sub:hover > a:after {
            top: 0;
            bottom: 0;
        }

        #cssmenu > ul > li.has-sub > a:before {
            content: "";
            position: absolute;
            top: 18px;
            right: 6px;
            border: 5px solid transparent;
            border-top: 5px solid #ffffff;
        }

        #cssmenu > ul > li.has-sub:hover > a:before {
            top: 18px;
        }

        #cssmenu > ul > li.has-sub:hover > a {
            /*padding-bottom: 14px;*/
            z-index: 999;
            border-color: #2B5681;
        }

        #cssmenu ul li.has-sub:hover > ul,
        #cssmenu ul li.has-sub:hover > div {
            display: block;
        }

        #cssmenu > ul > li.has-sub > a:hover,
        #cssmenu > ul > li.has-sub:hover > a {
            background: #2B5681;
            border-color: #2B5681;
        }

        #cssmenu ul li > ul,
        #cssmenu ul li > div {
            display: none;
            width: auto;
            position: absolute;
            top: 37px;
            background: #2B5681;
            border-radius: 0 0 5px 5px;
            z-index: 999;
            padding: 10px 0;
        }

        #cssmenu ul li > ul {
            width: 200px;
        }

        #cssmenu ul ul ul {
            position: absolute;
        }

        #cssmenu ul ul li:hover > ul {
            left: 100%;
            top: -10px;
            border-radius: 5px;
        }

        #cssmenu ul li > ul li {
            display: block;
            list-style: inside none;
            position: relative;
            margin: 0;
            padding: 0;
        }

            #cssmenu ul li > ul li a {
                outline: none;
                display: block;
                position: relative;
                font: 10pt verdana;
                color: #ffffff;
                text-decoration: none;
                text-shadow: 1px 1px 0 rgba(55, 110, 166, 0.6);
                margin: 0;
                padding: 8px 20px;
            }

        #cssmenu,
        #cssmenu ul ul > li:hover > a,
        #cssmenu ul ul li a:hover {
            background: #2B5681;
            background: -moz-linear-gradient(top, #2B5681 0%, #336699 100%);
            background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #2B5681), color-stop(100%, #336699));
            background: -webkit-linear-gradient(top, #2B5681 0%, #336699 100%);
            background: -o-linear-gradient(top, #2B5681 0%, #336699 100%);
            background: -ms-linear-gradient(top, #2B5681 0%, #336699 100%);
            background: linear-gradient(top, #2B5681 0%, #336699 100%);
        }

            #cssmenu > ul > li > a:hover {
                background: #336699;
                color: Orange;
            }

            #cssmenu ul ul a:hover {
                color: orange;
//                font-weight: bold;
            }

            #cssmenu > ul > li.has-sub > a:hover:before {
                border-top: 5px solid Orange;
            }

<div id='cssmenu'>
    <ul style="display: table;">
        <li style="width: 108px;" class='active'><a runat="server" href='~/Applications/Sentinel/Default.aspx'><span>Home</span></a></li>
        <li style="width: 118px;" class='has-sub'><a><span>Jobs</span></a>
            <ul>
                <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/Jobs.aspx'>Jobs List<span></span></a>
                </li>
                <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/AddJob.aspx'><span>Add New Job</span></a>
                </li>
            </ul>
        </li>
        <li style="width: 118px;" class='has-sub'><a><span>Quotes</span></a>
            <ul>
                <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/AddQuote.aspx'>Raise New Quote<span></span></a>
                </li>
                <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/ViewQuotes.aspx'><span>View Quotes</span></a>
                </li>
                <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/UploadQuote.aspx'><span>Upload New Quote</span></a>
                </li>
            </ul>
        </li>
        <li style="width: 108px;"><a runat="server" href='~/Applications/Sentinel/Locations.aspx'><span>Locations</span></a></li>
        <li style="width: 108px;"><a runat="server" href='~/Applications/Sentinel/Assets.aspx'><span>Assets</span></a></li>
        <li style="width: 118px;" class='has-sub'><a><span>Admin</span></a>
            <ul>
                <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/Administration/ContractorsAdmin.aspx'>Contractors<span></span></a>
                </li>
                <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/Administration/CreateNewUser.aspx'><span>Create New User Account</span></a>
                </li>
                <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/Administration/JobStatusAdmin.aspx'><span>Job Status Admin</span></a>
                </li>
                <li class='has-sub'><a runat="server" href='~/Applications/Sentinel/Administration/JobTypesAdmin.aspx' style="text-align: left;"><span>Job Types Admin</span></a>
                </li>
                <li class="has-sub"><a runat="server" href='~/Applications/Sentinel/Administration/ProjectAdmin.aspx' style="text-align: left;"><span>Project Admin</span></a>
                </li>
                <li class='has-sub'><a runat="server" style="text-align: left;" href='~/Applications/Sentinel/Administration/UserAdmin.aspx'><span>User Admin</span></a>
                </li>
            </ul>
        </li>
        <li><a runat="server" style="width: 108px;"><span>Reports</span></a></li>

        <li class='last' style="width: 125px;"><a runat="server" href='~/LoggedOut.aspx'><span>Log Out</span></a></li>
    </ul>
</div>