[note]布局：列等高，水平垂直居中，固定页脚

摘要：等高列布局两列结构两边都加上跟相等的负值，可以实现边框效果等同两列流体布局多列值要够大结构三列固定宽度结构三列自适应布局实用结构多列布局现代浏览器结构水平垂直

html结构：.wrap>.container>.sidebar+.main
marginLeft,marginRight两边都加上跟borderWidth相等的负值，可以实现边框效果

/*1: 等同*/
.container {
  border-left-width: 200px;/*1*/
}
.sidebar {
  float: left;
  width: 200px;/*1*/
  margin-left: -200px;/*1*/
  margin-right: -1px;
  border-right: 1px solid #888;
}
.main {
  float: left;
  margin-left: -1px;
  border-left: 1px solid #888;
}

http://codepen.io/zplus/pen/N...

.main {
  width: 100%;
  border-right: 220px solid #f00;
  margin-right: -220px;
}
.sidebar {
  width: 220px;
  background: #f00;
}

http://codepen.io/zplus/pen/X...

padding,margin值要够大
html结构：.container>.left+.main+.right

.container {
  overflow: hidden;
}
.column {
  margin-bottom: -99999px;
  padding-bottom: 99999px;
}

http://codepen.io/zplus/pen/w...

html结构：.wrap>.container>.main+.left+.right

.container {
  width: 520px;
  border-left: 220px solid #0f0; /*==leftWidth*/
  border-right: 220px solid #f00;/*==rightWidth*/
}
.left {
  float: left;
  width: 220px;
  margin-left: -220px;
}
.main {
  float: left;
  width: 520px;
  margin-right: -520px;
}
.right {
  float: right;
  width: 220px;
  margin-right: -220px;
}

http://codepen.io/zplus/pen/J...

html结构：.container>.main+.left+.right

.container {
  width: 100%;
  float: left;
  border-left: 220px solid #0f0;
  border-right: 220px solid #f00;
  display: inline; /*IE*/
}
.main {
  float: left;
  width: 100%;
  margin-right: -100%;
}
.left {
  float: left;
  width: 220px;
  margin-left: -220px;
}
.right {
  float: right;
  width: 220px;
  margin-right: -220px;
}

http://codepen.io/zplus/pen/b...

html结构：.table>.table-row>.table-cell+.table-cell+.table-cell

.table {
  display: table;
  &-row {
    display: table-row;
  }
  &-cell {
    display: table-cell;
    width: 33%;
  }
}

http://codepen.io/zplus/pen/b...

body {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;/*firefox下需要*/
}

http://codepen.io/zplus/pen/m...

img {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

https://codepen.io/zplus/pen/...

运用inline-block配合空标签，这里使用伪元素替代

body {
  text-align: center;
  &:after {
    content: "";
    display: inline-block;
    vertical-align: middle;
    height: 100%;
    width: 0;
  }
}

https://codepen.io/zplus/pen/...

html结构：.wrap>.container+.footer

.wrap {
  display: table;
  table-layout: fixed;
  > div {
      display: table-row;
      height: 1px;
  }
  .container {
    height: auto;
  }
}

http://codepen.io/zplus/pen/o...

html结构：.wrap>.container+.footer

  html, body {
    height: 100%;
  }
  #{$root-selector} {
    min-height: 100%;
    height: auto !important;
    height: 100%;
    margin-bottom: -$footer-height;
    &:after {/*可用空标签替代*/
      content: "";
      display: block;
      height: $footer-height;
    }
  }
  #{$footer-selector} {
    height: $footer-height;
  }

http://codepen.io/zplus/pen/q...

html结构：.wrap>.container+.footer

.wrap {
  position: relative;
}
.container {
  padding-bottom: 60px; /*==footerHeight*/
}
.footer {
  position: absolute; /*基于wrap的定位*/
  bottom: 0;
  height: 60px; /*footerHeight*/
}

http://codepen.io/zplus/pen/X...

html结构：.wrap>.container^+.footer

html, body {
  height: 100%;
}
.wrap {
  min-height: 100%;
  height: auto !important;
  height: 100%;
}
.container {
  padding-bottom: 60px; /*==footerHeight*/
}
.footer {
  margin-top: -60px; /*==footerHeight*/
  height: 60px;
}

http://codepen.io/zplus/pen/x...

http://codepen.io/zplus/pen/O...

在垂直居中的元素上添加伪元素，设置伪元素的高==父级容器的高，然后为文本添加vertical-align:middle

.ghost-center {
  position: relative;
  &::before {
    content: "";
    display: inline-block;
    height: 100%;
    width: 1%;
    vertical-align: middle;
  }
  p {
    display: inline-block;
    vertical-align: middle;
  }
}

http://codepen.io/zplus/pen/M...

@mixin center($width: null, $height: null) {
  position: absolute;
  top: 50%;
  left: 50%;
  
  @if not $width and not $height {
    transform: translate(-50%, -50%);
  } @else if $width and $height {
    width: $width;
    height: $height;
    margin: -($width/2) #{0 0} -($height/2);
  } @else if not $height {
    width: $width;
    margin-left: -($width/2);
    transform: translateY(-50%);
  } @else {
    height: $height;
    margin-top: -($height/2);
    transform: translateX(-50%);
  }
}

/*flexbox方法*/
@mixin center-children {
  display: flex;
  justify-content: center;
  align-items: center;
}

http://codepen.io/zplus/pen/p...

参考网址：

再谈等高列布局、水平垂直居中与置顶页脚
八种创建等高列布局
CSS居中完整指南
使用Sass制作居中效果