bootstrap源码分析之foRm、navbar

1、按层次结构分：form-group -> form-control/input-group/form-static-control -> 各类标签
2、Form-group/form-control/input-group/form-static-control之类的容器，分为两种显示方式：block、inline-block。而实现input-group水平用的是table-cell。

.input-group {
 display: inline-table;
 vertical-align: middle;
 .input-group-addon,
 .input-group-btn,
 .form-control {
 width: auto;
 }
}

3、Input-group-addon：类如果插入网页文字图标，会向上一个像素的错位

解决方案：glyphicon不能与其他样式合并使用，而是内部嵌套使用即可，因为glyphicon对top有1个像素的设置：

.glyphicon {
 position: relative;
 top: 1px;
 display: inline-block;
 font-family: 'Glyphicons Halflings';
 font-style: normal;
 font-weight: normal;
 line-height: 1;
 -webkit-font-smoothing: antialiased;
 -moz-osx-font-smoothing: grayscale;
}

二、导航条（navbar）

源码文件：
_navbar.scss

.navbar-toggle {
 position: relative;
 float: right;
 margin-right: $navbar-padding-horizontal;
 padding: 9px 10px;
 @include navbar-vertical-align(34px);
 background-color: transparent;
 background-image: none; // Reset unusual Firefox-on-Android default style; see https://github.com/necolas/normalize.css/issues/214
 border: 1px solid transparent;
 border-radius: $border-radius-base;

 // We remove the `outline` here, but later compensate by attaching `:hover`
 // styles to `:focus`.
 &:focus {
 outline: 0;
 }

 // Bars
 .icon-bar {
 display: block;
 width: 22px;
 height: 2px;
 border-radius: 1px;
 }
 .icon-bar + .icon-bar {
 margin-top: 4px;
 }

 @media (min-width: $grid-float-breakpoint) {
 display: none;
 }
}