html - 这个额外的空间从何而来？

Question

正如你在这里看到的http://jsfiddle.net/FqW4R/在下图中，我的菜单项与“ Logo ”和“社交”并不完全一致。菜单类别(菜单 I、菜单 2 等)和子项之间也存在巨大差距。当我查看我的代码时，我没有看到额外的填充或任何可能导致此类问题的类似内容。对此有什么想法吗？非常感谢

Html, body {
    margin: 0;
    padding: 0;
    background: #fff;
    font-family: 'Open Sans', sans-serif; 
}

#logo {
    position: absolute;
    top: 35px;
    left: 20px;
    color: #000;
    font-size: 20px;
}

/* mainmenu */

#mainmenu {
    float:right;
    margin-top: 35px;
    padding-bottom: 10px; 
    overflow: hidden;
}
#mainmenu ul {
    float: right;
    margin: 0;
    color: #000;
    list-style: none;
}
#mainmenu ul li {
    display: inline-block;
    float: left;
    width: 140px;
    line-height: 20px;
}
#mainmenu>ul>li {
    margin-left: 20px;
}
#mainmenu ul li a {
    display: block;
    text-decoration: none;
    font-weight:600;
    font-size: 12px;
}
#mainmenu ul li a, #mainmenu ul ul:hover li a {
    color: #333;
    -webkit-transition-timing-function: ease-out, ease-in, linear, ease-in-out;
    -moz-transition-timing-function: ease-out, ease-in, linear, ease-in-out;
    -ms-transition-timing-function: ease-out, ease-in, linear, ease-in-out;
    -o-transition-timing-function: ease-out, ease-in, linear, ease-in-out;
    transition-timing-function: ease-out, ease-in, linear, ease-in-out;
    -webkit-transition-duration: .4s, .4s, .4s, .4s;
    -moz-transition-duration: .4s, .4s, .4s, .4s;
    -ms-transition-duration: .4s, .4s, .4s, .4s;
    -o-transition-duration: .4s, .4s, .4s, .4s;
    transition-duration: .4s, .4s, .4s, .4s;
    -webkit-transition-property: all, -webkit-transform;
    -moz-transition-property: all, -moz-transform;
    -ms-transition-property: all, -ms-transform;
    -o-transition-property: all, -o-transform;
    transition-property: all, transform;
}
#mainmenu ul ul li a:hover, #mainmenu ul ul li.current-menu-item a {
    color: #005EBC;
    -webkit-transition-timing-function: ease-out, ease-in, linear, ease-in-out;
    -moz-transition-timing-function: ease-out, ease-in, linear, ease-in-out;
    -ms-transition-timing-function: ease-out, ease-in, linear, ease-in-out;
    -o-transition-timing-function: ease-out, ease-in, linear, ease-in-out;
    transition-timing-function: ease-out, ease-in, linear, ease-in-out;
    -webkit-transition-duration: .4s, .4s, .4s, .4s;
    -moz-transition-duration: .4s, .4s, .4s, .4s;
    -ms-transition-duration: .4s, .4s, .4s, .4s;
    -o-transition-duration: .4s, .4s, .4s, .4s;
    transition-duration: .4s, .4s, .4s, .4s;
    -webkit-transition-property: all, -webkit-transform;
    -moz-transition-property: all, -moz-transform;
    -ms-transition-property: all, -ms-transform;
    -o-transition-property: all, -o-transform;
    transition-property: all, transform;
}

#social {
position: absolute;
    float:right;
    right: 10px;
    Color: blue;
    margin-top: 35px;
}

HTML

  <div id="logo">Logo</div>  <!-- End DIV Logo -->
  <div id="mainmenu">
    <ul>
      <li>
        <h5>Menu I</h5>
        <ul>
          <li><a title="" href="">Biography</a> </li>
          <li><a title="" href="">Publications</a> </li>
        </ul>
      <li>
        <h5>Menu 2</h5>
        <ul>
          <li><a title="" href="">Demo</a> </li>
          <li><a title="" href="">Features</a> </li>
          <li><a title="" href="">Comparison</a> </li>
        </ul>
      </li>
      <li>
        <h5>Menu 3</h5>
        <ul>
          <li><a title="" href="">Item 1</a> </li>
          <li><a title="" href="">Item 2</a> </li>
          <li><a title="" href="">Item 3</a> </li>
        </ul>
      </li>
      <li>
        <h5>Menu 4</h5>
        <ul>
          <li><a title="" href="">ddfd</a> </li>
          <li><a title="" href="">dsfd</a> </li>
        </ul>
      </li>
    </ul>
  </div>  <!-- End DIV Main Menu -->
 <div id="social">Social</div><!-- End DIV Social -->

Answer 1

首先，您应该使用 CSS Reset，因为如果您不重置元素，浏览器将对您的元素应用一些默认样式，这是您不想要的，是吗？你可以谷歌出来，那里会得到很多，如果你想保持简单但你想重置，你可以使用下面的代码块并将其粘贴到你的 CSS 中

* {
    margin: 0;
    padding: 0;
}

Demo (减少间距)

看来你应该学习定位，你正在使用 position: absolute; 元素，没有将元素包装在 position: relative; 容器中，这样，你的 position: absolute; 元素会在野外流出。另外，我认为您不想使用 absolute，在这里使用 float 比较合适。

了解定位的重要性..

What you are doing

What should you do (看到 position: relative; 了吗？)

每个菜单之间的水平间距是因为您使用显式 width

Demo

此外，如果您使用float，则不需要display: inline-block;

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我建议你学习CSS Positioning和 Floats