前言

个人在做项目的过程中总结归纳的一些常用Mixin，现在分享出来供大家学习。
基于Less编写。但是CSS预处理器都是相通的，你可以很轻易的修改成Sass、Stylus
代码免不了错误和Bug，如果你能帮我修改或者补充万分感谢！！
参考了一些开源库，如：est、csslab等
Usage

/**
* 作品：mixin.less
* 更新：2017年12月14日
* 简介：1. 一个基于 Less 的样式工具库，封装了常用 mixin，帮助您更轻松地书写 Less 代码。
*       2. 只在调用时才输出代码，减少代码冗余，避免样式污染
*       3. 不自带兼容前缀，减少代码量，而建议采用工具生成，如 postcss、Autoprefixer、less-plugin-autoprefix 等
*       4. 附带 IE 各类 Hack
*/

/*-------------------------------------
├   布局                              ┆
└------------------------------------*/

// 盒子宽高
.size(@w, @h) { width: @w; height: @h; }

// 最小尺寸, 兼容IE6
.min-width(@min-w) { min-width: @min-w; _width: @min-w; }
.min-height(@min-h) { min-height: @min-h; _height: @min-h; }

// 内联块级元素, 兼容IE6
.dib() { display: inline-block; *display: inline; *zoom: 1; }

// 固定定位, 兼容IE6
.fixed() { position: fixed; _position: absolute; *zoom: 1; }

// 统一盒模型
.border-box() {
  *, *:after, *:before { -webkit-box-sizing: border-box; -moz-box-sizing: border-box; box-sizing: border-box; }
}

// 文字图片居中
.center(text-x) { text-align: center; }
.center(text-y) { display: table-cell; vertical-align: middle; }

// 块级元素水平居中
.center(auto-x) { display: block; margin-left: auto; margin-right: auto; }

// 居中, 不确定尺寸, 不兼容 IE6
.center(unknown) { position: absolute; top: 0; left: 0; right: 0; bottom: 0; margin: auto; }
.center(unknown-x) { position: absolute; left: 0; right: 0; margin-left: auto; margin-right: auto; }
.center(unknown-y) { position: absolute; top: 0; bottom: 0; margin-top: auto; margin-bottom: auto; }

// 居中, 确定尺寸, 兼容 IE6
.center(known, @w, @h) {
  .size(@w, @h);
  position: absolute; top: 50%; left: 50%; margin-top: -(@w / 2); margin-left: -(@h / 2);
}
.center(known-x, @w) {
  width: @w;
  position: absolute; left: 50%; margin-left: -(@h / 2);
}
.center(known-y, @h) {
  height: @h;
  position: absolute; top: 50%; margin-top: -(@w / 2);
}

// 居中, CSS3 平移方式, 兼容性不行
.center(translate) { position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); }

// 居中, Flex 方式, 兼容性不行
.center(flex) { display: flex; align-items: center; justify-content: center; }

// 多个子项布局
.list(float, @w: 25%) { float: left; width: @w; }
.list(inline, @w: 25%) { .dib(); width: @w; }
.list(flex) { flex: 1; }

// 遮罩层, 全屏遮罩、区域遮罩
.over-screen(fixed) { .fixed(); top: 0; left: 0; right: 0; bottom: 0; }
.over-screen(absolute) { position: absolute; top: 0; left: 0; right: 0; bottom: 0; }

// 容器宽高比固定
// 100* 1/1 = 100%
// 100* 3/4 = 75%
.fixed-ratio(@padding-top: 100%) {
  position: relative; width: 100%; height: 0; padding-top: @padding-top;
  img { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }
}

// 扩展点击区域
.extend-click() {
  position: relative;
  &:before { content: ''; position: absolute; top: -10px; left: -10px; right: -10px; bottom: -10px; }
}

// 定宽居中页面布局
.layout-page(@width: 1200px) { width: @width; margin-left: auto; margin-right: auto; }

// 侧边栏
// 主要区域：overflow: hidden; margin-left: xx; margin-right: xx;
.sidebar(left, @width) { position: absolute; top: 0; left: 0; width: @width; }
.sidebar(right, @width) { position: absolute; top: 0; right: 0; width: @width; }

/*-------------------------------------
├   字体                              ┆
└------------------------------------*/

// 字体大小
.fz(@fz) { font-size: @fz; }

// 字体大小与行高
.fz(@fz, @lh) { font-size: @fz; line-height: @lh; }

// 字体大小、行高、高度
.fz(@fz, @h, @lh: @h) { font-size: @fz; height: @h; line-height: @lh; }

// 行高与高度
.lh(@h, @lh: @h) { height: @h; line-height: @lh; }

// 字体颜色, 包括链接与非链接
.color(@color) { color: @color;}

// 字体颜色 + 自身 Hover
.color(@color, @hovercolor) {
  color: @color;
  &:hover { color: @hovercolor; }
}

// 字体颜色 + 链接 Hover
.color(@color, @acolor, @hovercolor) {
  color: @color;
  a {
    color: @acolor;
    &:hover { color: @hovercolor; }
  }
}

// 正常字体样式
.normal-font() { font-weight: normal; font-style: normal; }

// 辅助性文字（灰色）
.assist-font(@color: #b0b0b0, @fz: 14px) { color: @color; font-size: @fz; }

// 禁止换行, 文本溢出省略号显示 (一行)
.ellipsis() {
  white-space: normal; word-wrap: break-word; word-break: break-all;
  -o-text-overflow: ellipsis; -ms-text-overflow: ellipsis; text-overflow:ellipsis; overflow:hidden;
}

// 文本溢出省略号显示 (多行)
// 只支持 webkit 浏览器, 解决方案：高度 = 行高*行数
// height: 90px; line-height: 30px; -webkit-line-clamp: 3;
.ellipsis-mult(@n: 3) {
  display: -webkit-box; -webkit-box-orient: vertical;-webkit-line-clamp: @n; word-break: break-all;
  -o-text-overflow: ellipsis; -ms-text-overflow: ellipsis; text-overflow:ellipsis; overflow: hidden;
}

// 书写模式：牌匾从右至左水平单行排版效果、文笺从右至左、从上至下排版效果
.retext(x) { direction: rtl; unicode-bidi: bidi-override; }
.retext(y) { writing-mode: tb-rl; writing-mode: vertical-rl; }

// 文字透明
.transparent-text() { font: 0/0 serif; text-shadow: none; color: transparent; }

// 文字隐藏（常用于SEO优化）
// <a href="" title="Logo SEO 优化 "><h1 class="logo">xx</h1></a>
.hidden-text() { text-indent : -9999px; overflow: hidden; text-align: left; }

// 文字外发光效果
.glow-text(@r: 10px, @color: gold) { text-shadow: 0 0 @r @color; }

/*-------------------------------------
├   图像                              ┆
└------------------------------------*/

// 用 max-width 来防止图片撑破容器
.max-img() { display: block; max-width: 100%; height: auto; }

// 2x 3x 背景图片
.bg-image(@url) {
  background-image: url("@url + '@2x.png'");
  @media (-webkit-min-device-pixel-ratio: 3), (min-device-pixel-ratio: 3) {
    background-image: url("@url + '@3x.png'");
  }
}

// 全屏大图背景
.fullscreen-bg(@url) {
  width: 100vw;
  height: 100vh;
  background: url(@url) no-repeat 50% 50%;
  background-size: cover;
}

// 滤镜: 将彩色照片显示为黑白照片
.grayscale() {
  filter: grayscale(100%);
  -webkit-filter: grayscale(100%);
  -moz-filter: grayscale(100%);
  -ms-filter: grayscale(100%);
  -o-filter: grayscale(100%);
}

/*-------------------------------------
├   动效                              ┆
└------------------------------------*/

// 链接默认无下划线，hover后有下划线的样式
.hover-link() {
  text-decoration: none;
  &:hover { text-decoration: underline; }
}

// 将链接变成默认的文字样式
.unstyled-link() {
  color: inherit;
  cursor: inherit;
  text-decoration: inherit;
  &:active, &:focus { outline: none; }
}

// 盒子阴影
// box-shadow: 水平阴影的位置, 垂直阴影的位置, 模糊距离, 阴影的大小, 阴影的颜色, 阴影开始方向（默认是从里往外，设置inset就是从外往里）;
// box-shadow: h-shadow v-shadow blur spread color inset;
.box-shadow() {
  box-shadow: 0px 14px 26px 0px rgba(0, 0, 0, 0.1);
}

// 盒子 Hover
.box-hover() {
  // box-shadow: 0px 1px 2px 0px rgba(84, 107, 107, .4);
  transition: all .2s linear;
  &:hover {
    box-shadow: 0 15px 30px rgba(0, 0, 0, .1);
    transform: translate3d(0, -2px, 0);
  }
}

.box-hover2() {
  transition: transform .5s ease;
  &:hover {
    transform: translateX(10px);
  }
}

// 三维闪动 bug 处理
.transform-fix() { -webkit-backface-visibility: hidden; -webkit-transform-style: preserve-3d; }

// Animation
.ani(@name, @time: 1s, @ease: ease-in-out, @fillmode: forwards) {
  animation-name: @name;
  animation-duration: @time;
  animation-timing-function: @ease;
  animation-fill-mode: @fillmode;
}

/*-------------------------------------
├   功能                              ┆
└------------------------------------*/

// 浮动, 兼容 IE6
.fl() { float: left; *display: inline; _display:inline; }
.fr() { float: right; *display: inline; _display:inline; }

// 清除浮动
.clearfix() {
  *zoom: 1;
  &:after { display: block; clear: both; content: ''; visibility: hidden; height: 0; }
}
.clearfix(table) {
  *zoom: 1;
  &:before, &:after { content: " "; display: table; clear: both; }
}

// 禁止文本被选择
.user-select() { -webkit-user-select: none; -moz-user-select: none; -ms-user-select: none; user-select: none; }

// 隐藏鼠标手势
.hide-cursor() { cursor: none !important; }

// 鼠标禁用样式，但仍然可以触发事件
// <input type="text" disabled="disabled">
.disabled() { cursor: not-allowed; }

// 禁用元素事件
// 1. 阻止任何点击动作的执行
// 2. 使链接显示为默认光标(cursor:default)
// 3. 阻止触发hover和active状态
// 4. 阻止JavaScript点击事件的触发
.pointer-events() { pointer-events: none; }

// 模糊
.blur(@blur: 10px) {
  filter: blur(@blur);
  -webkit-filter: blur(@blur);
  -moz-filter: blur(@blur);
  -o-filter: blur(@blur);
  -ms-filter: blur(@blur);
  filter: progid:DXImageTransform.Microsoft.Blur(PixelRadius='@{blur}');
  *zoom: 1;
}

// 透明度, 兼容 IE8
.opacity(@opacity: 20) { opacity: @opacity / 100; filter: alpha(opacity=@opacity); }

// 用伪类来显示打印时 a 标签的链接
.print-link() {
  @media print {
    a[href]:after { content: " (" attr(href) ") "; }
  }
}

// 隔行换色
.zebra-lists(odd, @color) {
  &.odd {
    >li:nth-child(odd) { background-color: @color; }
  }
}
.zebra-lists(even, @color) {
  &.even {
    >li:nth-child(even) { background: green; }
  }
}

// 首字下沉
.first-letter(@font-size: 6em) {
  &::first-letter{
    float: left;
    line-height: 1;
    font-size: @font-size;
  }
}

// 特殊标记段落第一行
.first-line() {
  &::first-line{
    color: red
  }
}

// 美化选中文本
.beauty-select() {
  &::selection{
   color: #fff;
   background-color: #6bc30d;
   text-shadow: none;
  }
}

// 美化占位符 placeholder 样式
.beauty-placeholder(@fz, @color: #999, @align: left) {
  &:-moz-placeholder { font-size: @fz; color: @color; text-align: @align; }
  &:-ms-input-placeholder { font-size: @fz; color: @color; text-align: @align; }
  &::-webkit-input-placeholder { font-size: @fz; color: @color; text-align: @align; }
}

// 美化占位符 placeholder 样式（自定义属性和值）
.beauty-placeholder(custom, @property, @value) {
  &:-moz-placeholder { @{property}: @value; }
  &:-ms-input-placeholder { @{property}: @value; }
  &::-webkit-input-placeholder { @{property}: @value; }
}

/*-------------------------------------
├   图形                              ┆
└------------------------------------*/

// 三角形
.triangle(@width: 4px,@color: #000) {
  display: inline-block;
  width: 0;
  height: 0;
  vertical-align: middle;
  border-top: @width solid @color;
  border-left: @width solid transparent;
  border-right: @width solid transparent;
}

// 三角形箭头气泡效果, IE6-7 无表现
.arrow(top, @w: 10px, @color, @x: 50%) {
  position: relative;
  &:before { position: absolute; bottom: 100%; left: @x; content: " "; height: 0; width: 0; pointer-events: none; border-style: solid; border-color: transparent; border-bottom-color: @color; border-width: unit(@w, px); @margin: -@w; margin-left: unit(@margin, px); }
}
.arrow(right, @w: 10px, @color, @y: 50%) {
  position: relative;
  &:before { position: absolute; left: 100%; top: @y; content: " "; height: 0; width: 0; pointer-events: none; border-style: solid; border-color: transparent; border-left-color: @color; border-width: unit(@w, px); @margin: -@w; margin-top: unit(@margin, px); }
}
.arrow(bottom, @w: 10px, @color, @x: 50%) {
  position: relative;
  &:before { position: absolute; top: 100%; left: @x; content: " "; height: 0; width: 0; pointer-events: none; border-style: solid; border-color: transparent; border-top-color: @color; border-width: unit(@w, px); @margin: -@w; margin-left: unit(@margin, px); }
}
.arrow(left, @w: 10px, @color, @y: 50%) {
  position: relative;
  &:before { position: absolute; right: 100%; top: @y; content: " "; height: 0; width: 0; pointer-events: none; border-style: solid; border-color: transparent; border-right-color: @color; border-width: unit(@w, px); @margin: -@w; margin-top: unit(@margin, px); }
}

// 三角形箭头气泡效果, 带边框
.arrow-with-border(top, @w: 10px, @color, @border-w: 1px, @border-color, @x: 50%) {
  position: relative;
  &:before, &:after { bottom: 100%; left: @x; content: " "; height: 0; width: 0; position: absolute; pointer-events: none; border-style: solid; border-color: transparent; }
  &:after { border-bottom-color: @color; border-width: unit(@w, px); @margin: -@w; margin-left: unit(@margin, px); }
  &:before { border-bottom-color: @border-color; @arrbo: @w+@border-w; border-width: unit(@arrbo, px); @margin-bo: -@arrbo; margin-left: unit(@margin-bo, px); }
}
.arrow-with-border(bottom, @w: 10px, @color, @border-w: 1px, @border-color, @x: 50%) {
  position: relative;
  &:before, &:after { top: 100%; left: @x; content: " "; height: 0; width: 0; position: absolute; pointer-events: none; border-style: solid; border-color: transparent; }
  &:after { border-top-color: @color; border-width: unit(@w, px); @margin: -@w; margin-left: unit(@margin, px); }
  &:before { border-top-color: @border-color; @arrbo: @w+@border-w; border-width: unit(@arrbo, px); @margin-bo: -@arrbo; margin-left: unit(@margin-bo, px); }
}
.arrow-with-border(left, @w: 10px, @color, @border-w: 1px, @border-color, @y: 50%) {
  position: relative;
  &:before, &:after { top: @y; right: 100%; content: " "; height: 0; width: 0; position: absolute; pointer-events: none; border-style: solid; border-color: transparent; }
  &:after { border-right-color: @color; border-width: unit(@w, px); @margin: -@w; margin-top: unit(@margin, px); }
  &:before { border-right-color: @border-color; @arrbo: @w+@border-w; border-width: unit(@arrbo, px); @margin-bo: -@arrbo; margin-top: unit(@margin-bo, px); }
}
.arrow-with-border(right, @w: 10px, @color, @border-w: 1px, @border-color, @y: 50%) {
  position: relative;
  &:before, &:after { top: @y; left: 100%; content: " "; height: 0; width: 0; position: absolute; pointer-events: none; border-style: solid; border-color: transparent; }
  &:after { border-left-color: @color; border-width: unit(@w, px); @margin: -@w; margin-top: unit(@margin, px); }
  &:before { border-left-color: @border-color; @arrbo: @w+@border-w; border-width: unit(@arrbo, px); @margin-bo: -@arrbo; margin-top: unit(@margin-bo, px); }
}

/*-------------------------------------
├   组件                              ┆
└------------------------------------*/

// 吸顶导航
.fix-header(@h: 70px) {
  .fixed();
  top: 0;
  left: 0;
  width: 100%;
  height: @h;
  z-index: 1000;
  // background-color: rgba(256, 256, 256, .92);
  // border-bottom: 1px solid rgba(7, 17, 27, 0.1);
  // box-shadow: 0px 0px 20px rgba(0,0,0,0.2);
}

// 吸底导航
.fix-header(@h: 70px) {
  .fixed();
  left: 0;
  bottom: 0;
  width: 100%;
  height: @h;
  z-index: 1000;
}

// 输入框
.input-text() {
  display: block;
  width: 100%;
  padding: 4px 8px;
  font-size: 14px;
  line-height: 1.42858;
  color: #333;
  border: 1px solid #ddd;
  background-color: #fff;
  border-radius: 3px;
}

// 分割线
// <span class="separator">|/-</span>
.separator() {
  margin: 0 10px;
  color: #999;
  font-size: 14px;
}

// 分割线 / (面包屑导航)
.separator2() {
  &:before {
    padding: 0 5px;
    color: #ccc;
    content: "/\00a0";
  }
}

// <hr class="hr">
// 支付宝：我也是有底线的
.hr() {
  height: 1px;
  margin: 10px 0;
  border: 0;
  clear: both;
  background-color: #e2e2e2;
}

// 改装的 fieldset
// <fieldset><legend>返璞归真</legend></fieldset>
.fieldset() {
  border-color: #d2d2d2;
  border-width: 1px 0 0;
  border-style: solid;
  legend {
    padding: 0 20px;
    text-align: center;
    font-size: 20px;
    font-weight: 300;
  }
}

// 引用区块（模仿 Layui）
// <div class="blockquote">Lorem ipsum dolor sit amet.</div>
.blockquote() {
  margin-bottom: 10px;
  padding: 15px;
  line-height: 22px;
  border-left: 5px solid #009688;
  border-radius: 0 2px 2px 0;
  background-color: #f2f2f2;
}

// 徽章 (椭圆、小圆点)
// <span class="badge">10</span>
.badge(...) {
  position: relative;
  display: inline-block;
  font-size: 12px;
  color: #fff;
  background-color: #FF5722;
}
.badge(ellipse) {
  min-width: 8px;
  height: 18px;
  padding: 2px 6px;
  text-align: center;
  line-height: 18px;
  border-radius: 9px;
}
.badge(dot) {
  width: 8px;
  height: 8px;
  border-radius: 50%;
}

// 关闭按钮
// <button class="close" type="button"><span>&times;</span></button>
.close() {
  position: relative;
  -webkit-appearance: none;
  padding: 0;
  cursor: pointer;
  background: 0 0;
  border: 0;
  font-size: 20px;
  font-weight: 700;
  line-height: 1;
  color: #000;
  text-shadow: 0 1px 0 #fff;
  filter: alpha(opacity=20);
  opacity: .2;
  &:hover {
    color: #000;
    text-decoration: none;
    cursor: pointer;
    filter: alpha(opacity=50);
    opacity: .5;
  }
  &:before {
    content: '';
    position: absolute;
    top: -10px;
    left: -10px;
    right: -10px;
    bottom: -10px;
  }
}

// 1 像素边框问题
.onepx(...) {
  position: relative;
  &:after {
    content: '';
    display: block;
    position: absolute;
    left: 0;
    width: 100%;
    border-top: 1px solid rgba(7, 17, 27, 0.1);
    transform: scaleY(0.5);
  }
}
.onepx(top) { &:after { top: 0; } }
.onepx(bottom) { &:after { bottom: 0; } }
.onepx-easy(top, @color: #ccc) { box-shadow: inset 0px -1px 1px -1px @color; }
.onepx-easy(bottom, @color: #ccc) { box-shadow: inset 0px 1px 1px -1px @color; }