html - 中心 CSS 菜单

Question

如何让这个菜单 css 居中？

这里是 CSS:

@import url(http://fonts.googleapis.com/css?family=Open+Sans);
#mainMenu,
#mainMenu ul,
#mainMenu ul li,
#mainMenu ul li a,
#mainMenu #menu-button {
  margin: 0;
  padding: 0;
  border: 0;
  list-style: none;
  line-height: 1;
  display: block;
  position: relative;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}
#mainMenu:after,
#mainMenu > ul:after {
  content: ".";
  display: block;
  clear: both;
  visibility: hidden;
  line-height: 0;
  height: 0;
}
#mainMenu #menu-button {
  display: none;
}
#mainMenu {
  width: auto;
  font-family: 'Open Sans', sans-serif;
  line-height: 1;
  background: #eff1f3;
}
#menu-line {
  position: absolute;
  top: 0;
  left: 0;
  height: 3px;
  background: #009ae1;
  -webkit-transition: all 0.25s ease-out;
  -moz-transition: all 0.25s ease-out;
  -ms-transition: all 0.25s ease-out;
  -o-transition: all 0.25s ease-out;
  transition: all 0.25s ease-out;
}
#mainMenu > ul > li {
  float: left;
}
#mainMenu.align-center > ul {
  font-size: 0;
  text-align: center;
}
#mainMenu.align-center > ul > li {
  display: inline-block;
  float: none;
}
#mainMenu.align-center ul ul {
  text-align: left;
}
#mainMenu.align-right > ul > li {
  float: right;
}
#mainMenu.align-right ul ul {
  text-align: right;
}
#mainMenu > ul > li > a {
  padding: 20px;
  font-size: 12px;
  text-decoration: none;
  text-transform: uppercase;
  color: #000000;
  -webkit-transition: color .2s ease;
  -moz-transition: color .2s ease;
  -ms-transition: color .2s ease;
  -o-transition: color .2s ease;
  transition: color .2s ease;
}
#mainMenu > ul > li:hover > a,
#mainMenu > ul > li.active > a {
  color: #009ae1;
}
#mainMenu > ul > li.has-sub > a {
  padding-right: 25px;
}
#mainMenu > ul > li.has-sub > a::after {
  position: absolute;
  top: 21px;
  right: 10px;
  width: 4px;
  height: 4px;
  border-bottom: 1px solid #000000;
  border-right: 1px solid #000000;
  content: "";
  -webkit-transform: rotate(45deg);
  -moz-transform: rotate(45deg);
  -ms-transform: rotate(45deg);
  -o-transform: rotate(45deg);
  transform: rotate(45deg);
  -webkit-transition: border-color 0.2s ease;
  -moz-transition: border-color 0.2s ease;
  -ms-transition: border-color 0.2s ease;
  -o-transition: border-color 0.2s ease;
  transition: border-color 0.2s ease;
}
#mainMenu > ul > li.has-sub:hover > a::after {
  border-color: #009ae1;
}
#mainMenu ul ul {
  position: absolute;
  left: -9999px;
}
#mainMenu li:hover > ul {
  left: auto;
}
#mainMenu.align-right li:hover > ul {
  right: 0;
}
#mainMenu ul ul ul {
  margin-left: 100%;
  top: 0;
}
#mainMenu.align-right ul ul ul {
  margin-left: 0;
  margin-right: 100%;
}
#mainMenu ul ul li {
  height: 0;
  -webkit-transition: height .2s ease;
  -moz-transition: height .2s ease;
  -ms-transition: height .2s ease;
  -o-transition: height .2s ease;
  transition: height .2s ease;
}
#mainMenu ul li:hover > ul > li {
  height: 32px;
}
#mainMenu ul ul li a {
  padding: 10px 20px;
  width: 160px;
  font-size: 12px;
  background: #333333;
  text-decoration: none;
  color: #dddddd;
  -webkit-transition: color .2s ease;
  -moz-transition: color .2s ease;
  -ms-transition: color .2s ease;
  -o-transition: color .2s ease;
  transition: color .2s ease;
}
#mainMenu ul ul li:hover > a,
#mainMenu ul ul li a:hover {
  color: #ffffff;
}
#mainMenu ul ul li.has-sub > a::after {
  position: absolute;
  top: 13px;
  right: 10px;
  width: 4px;
  height: 4px;
  border-bottom: 1px solid #dddddd;
  border-right: 1px solid #dddddd;
  content: "";
  -webkit-transform: rotate(-45deg);
  -moz-transform: rotate(-45deg);
  -ms-transform: rotate(-45deg);
  -o-transform: rotate(-45deg);
  transform: rotate(-45deg);
  -webkit-transition: border-color 0.2s ease;
  -moz-transition: border-color 0.2s ease;
  -ms-transition: border-color 0.2s ease;
  -o-transition: border-color 0.2s ease;
  transition: border-color 0.2s ease;
}
#mainMenu.align-right ul ul li.has-sub > a::after {
  right: auto;
  left: 10px;
  border-bottom: 0;
  border-right: 0;
  border-top: 1px solid #dddddd;
  border-left: 1px solid #dddddd;
}
#mainMenu ul ul li.has-sub:hover > a::after {
  border-color: #ffffff;
}
@media all and (max-width: 768px), only screen and (-webkit-min-device-pixel-ratio: 2) and (max-width: 1024px), only screen and (min--moz-device-pixel-ratio: 2) and (max-width: 1024px), only screen and (-o-min-device-pixel-ratio: 2/1) and (max-width: 1024px), only screen and (min-device-pixel-ratio: 2) and (max-width: 1024px), only screen and (min-resolution: 192dpi) and (max-width: 1024px), only screen and (min-resolution: 2dppx) and (max-width: 1024px) {
  #mainMenu {
    width: 100%;
  }
  #mainMenu ul {
    width: 100%;
    display: none;
  }
  #mainMenu.align-center > ul,
  #mainMenu.align-right ul ul {
    text-align: left;
  }
  #mainMenu ul li,
  #mainMenu ul ul li,
  #mainMenu ul li:hover > ul > li {
    width: 100%;
    height: auto;
    border-top: 1px solid rgba(120, 120, 120, 0.15);
  }
  #mainMenu ul li a,
  #mainMenu ul ul li a {
    width: 100%;
  }
  #mainMenu > ul > li,
  #mainMenu.align-center > ul > li,
  #mainMenu.align-right > ul > li {
    float: none;
    display: block;
  }
  #mainMenu ul ul li a {
    padding: 20px 20px 20px 30px;
    font-size: 12px;
    color: #000000;
    background: none;
  }
  #mainMenu ul ul li:hover > a,
  #mainMenu ul ul li a:hover {
    color: #000000;
  }
  #mainMenu ul ul ul li a {
    padding-left: 40px;
  }
  #mainMenu ul ul,
  #mainMenu ul ul ul {
    position: relative;
    left: 0;
    right: auto;
    width: 100%;
    margin: 0;
  }
  #mainMenu > ul > li.has-sub > a::after,
  #mainMenu ul ul li.has-sub > a::after {
    display: none;
  }
  #menu-line {
    display: none;
  }
  #mainMenu #menu-button {
    display: block;
    padding: 20px;
    color: #000000;
    cursor: pointer;
    font-size: 12px;
    text-transform: uppercase;
  }
  #mainMenu #menu-button::after {
    content: '';
    position: absolute;
    top: 20px;
    right: 20px;
    display: block;
    width: 15px;
    height: 2px;
    background: #000000;
  }
  #mainMenu #menu-button::before {
    content: '';
    position: absolute;
    top: 25px;
    right: 20px;
    display: block;
    width: 15px;
    height: 3px;
    border-top: 2px solid #000000;
    border-bottom: 2px solid #000000;
  }
  #mainMenu .submenu-button {
    position: absolute;
    z-index: 10;
    right: 0;
    top: 0;
    display: block;
    border-left: 1px solid rgba(120, 120, 120, 0.15);
    height: 52px;
    width: 52px;
    cursor: pointer;
  }
  #mainMenu .submenu-button::after {
    content: '';
    position: absolute;
    top: 21px;
    left: 26px;
    display: block;
    width: 1px;
    height: 11px;
    background: #000000;
    z-index: 99;
  }
  #mainMenu .submenu-button::before {
    content: '';
    position: absolute;
    left: 21px;
    top: 26px;
    display: block;
    width: 11px;
    height: 1px;
    background: #000000;
    z-index: 99;
  }
  #mainMenu .submenu-button.submenu-opened:after {
    display: none;
  }
}

这里是html

<div id='mainMenu'>
<ul>
  <li><a href='#'>Home</a></li>
  <li class='active has-sub'><a href='#'>Products</a>
    <ul>
      <li class='has-sub'><a href='#'>Product 1</a>
        <ul>
          <li><a href='#'>Sub Product</a></li>
          <li><a href='#'>Sub Product</a></li>
        </ul>
      </li>
      <li class='has-sub'><a href='#'>Product 2</a>
        <ul>
          <li><a href='#'>Sub Product</a></li>
          <li><a href='#'>Sub Product</a></li>
        </ul>
      </li>
    </ul>
  </li>
  <li><a href='#'>About</a></li>
  <li><a href='#'>Contact</a></li>
</ul>

请帮帮我。我真的很感激。我知道这不应该真的很难。已经很久没开发了，我的技能还在 sleep 哈哈。我正在尝试和重新搜索，但我没有找到任何有用的东西。谢谢!!!

Answer 1

尝试添加简单的 CSS

 #mainMenu {
    text-align: center;
}

#mainMenu ul {
    display: inline-block;
}

因为你没有提到 <li> width fiddle 不会显示准确的结果

JsFiddle