20 个超级实用的 CSS 技巧，帮助你成为更好的开发者-轻识

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英文 | https://javascript.plainenglish.io/20-css-tips-and-tricks-to-make-you-a-better-developer-43aa5b9d0c34

翻译 | 杨小爱

在开发项目中，修改输入占位符样式，多行文本溢出，隐藏滚动条，修改光标颜色，水平和垂直居中等等，这些都是我们非常熟悉的开发场景！前端开发者几乎每天都会和它们打交道，因此，我在这里给大家总结了20个超级实用的CSS技巧，一起来看看吧。

1.解决图片5px间距问题

你是否经常遇到图片底部多出5px间距的问题？不着急，这里有4种方法可以帮助你解决此问题。

解决方案 1：将 font-size: 0 设置为父元素

演示地址：https://codepen.io/qianlong/pen/VwrzoyE

具体实现代码如下：

HTML

<!DOCTYPE html><html lang="en"><head>  <meta charset="UTF-8">  <meta http-equiv="X-UA-Compatible" content="IE=edge">  <meta name="viewport" content="width=device-width, initial-scale=1.0">  <title>image 5px spacing</title></head><body>  <div class="img-container">    <img src="https://cdn-images-1.medium.com/max/1600/0*MU3iBxNwssZWt6Tj" alt="">  </div></body></html>

CSS

    html,body{      margin: 0;      padding: 0;    }
    .img-container{      background-color: lightblue;     /* Key Style */      font-size: 0;    }
    img{      width: 100%;    }

解决方案 2：将 display: block 设置为 img

演示地址：https://codepen.io/qianlong/pen/eYeGONM

具体实现代码如下：

HTML

<!DOCTYPE html><html lang="en"><head>  <meta charset="UTF-8">  <meta http-equiv="X-UA-Compatible" content="IE=edge">  <meta name="viewport" content="width=device-width, initial-scale=1.0">  <title>image 5px spacing</title></head><body>  <div class="img-container">    <img src="https://cdn-images-1.medium.com/max/1600/0*MU3iBxNwssZWt6Tj" alt="">  </div></body></html>

CSS

    html,body{      margin: 0;      padding: 0;    }
    .img-container{      background-color: lightblue;    }
    img{      width: 100%;      /* Key Style */      display: block;    }

解决方案 3：将 vertical-align: bottom 设置为 img

演示地址：https://codepen.io/qianlong/pen/jOaGNWw

具体实现代码如下：

HTML

<!DOCTYPE html><html lang="en"><head>  <meta charset="UTF-8">  <meta http-equiv="X-UA-Compatible" content="IE=edge">  <meta name="viewport" content="width=device-width, initial-scale=1.0">  <title>image 5px spacing</title></head><body>  <div class="img-container">    <img src="https://cdn-images-1.medium.com/max/1600/0*MU3iBxNwssZWt6Tj" alt="">  </div></body></html>

CSS

    html,body{      margin: 0;      padding: 0;    }
    .img-container{      background-color: lightblue;    }
    img{      width: 100%;      /* Key Style */      vertical-align: bottom;    }

方案四：给父元素设置line-height: 5px

演示地址：https://codepen.io/qianlong/pen/PoOJYzN

具体实现代码如下：

HTML

<!DOCTYPE html><html lang="en"><head>  <meta charset="UTF-8">  <meta http-equiv="X-UA-Compatible" content="IE=edge">  <meta name="viewport" content="width=device-width, initial-scale=1.0">  <title>image 5px spacing</title></head><body>  <div class="img-container">    <img src="https://cdn-images-1.medium.com/max/1600/0*MU3iBxNwssZWt6Tj" alt="">  </div></body></html>

CSS

    html,body{      margin: 0;      padding: 0;    }
    .img-container{      background-color: lightblue;      /* Key Style */      line-height: 5px;    }
    img{      width: 100%;    }

2.元素高度与窗口相同

演示地址：https://codepen.io/qianlong/pen/xxPXKXe

如何让元素和窗口一样高？示例代码如下：

<div class="app">  <div class="child">
  </div></div>

* {  margin: 0;  padding: 0;}
.child {  width: 100%;  /* Key Style */  height: 100vh;  background-image: linear-gradient(180deg, #2af598 0%, #009efd 100%);}

3.修改输入占位符样式

演示地址：https://codepen.io/qianlong/pen/JjOrPOq

第一个修改了，第二个没有修改。

<input type="text" class="placehoder-custom" placeholder="Please enter user name to search"><input type="text" placeholder="Please enter user name to search">

* {  margin: 0;  padding: 0;}
input {  width: 300px;  height: 30px;  border: none;  outline: none;  display: block;  margin: 15px;  border: solid 1px #dee0e9;  padding: 0 15px;  border-radius: 15px;}/* Key Style */.placehoder-custom::-webkit-input-placeholder {  color: #babbc1;  font-size: 12px;}

4. 使用“:not”选择器

演示地址：https://codepen.io/qianlong/pen/QWOqLQO

除了最后一个元素之外的所有元素都需要一些样式，使用 not 选择器会非常容易。

如下图：最后一个元素没有底边框。

<ul>  <li>    <span>cell</span>    <span>content</span>  </li>  <li>    <span>cell</span>    <span>content</span>  </li>  <li>    <span>cell</span>    <span>content</span>  </li>  <li>    <span>cell</span>    <span>content</span>  </li></ul>

* {  margin: 0;  padding: 0;}
html,body {  background-color: #f7f8fa;  height: 100%;}
ul,li {  list-style: none;  padding: 0 15px;  font-size: 14px;}
ul {  margin-top: 10px;  background-color: #fff;}
li {  height: 32px;  display: flex;  align-items: center;  justify-content: space-between;}/* Key Style */li:not(:last-child) {  border-bottom: 1px solid #ebedf0;}
li span:first-child {  color: #323233;}
li span:last-child {  color: #969799;}

5.使用flex布局智能固定一个元素在底部

演示地址：https://codepen.io/qianlong/pen/ZEaXzxM

当内容不够时，按钮应该在页面底部。当有足够的内容时，按钮应该跟随内容。当你遇到类似问题时，使用flex实现智能布局！

代码如下：

<div class="container">  <div class="main">I'm fatfish, 6 years of programming experience, like front-end, writing    and making friends,looking forward to becoming good friends with you.</div>  <div class="footer">rule</div></div>

* {  margin: 0;  padding: 0;}
.container {  height: 100vh;  /* Key Style */  display: flex;  flex-direction: column;  justify-content: space-between;}
.main {  /* Key Style */  flex: 1;  background-image: linear-gradient(    45deg,    #ff9a9e 0%,    #fad0c4 99%,    #fad0c4 100%  );  display: flex;  align-items: center;  justify-content: center;  color: #fff;}
.footer {  padding: 15px 0;  text-align: center;  color: #ff9a9e;  font-size: 14px;}

6.使用“caret-color”修改光标颜色

演示地址：https://codepen.io/qianlong/pen/YzErKvy

有时需要修改光标的颜色。现在是插入符号颜色显示时间。

<input type="text" class="caret-color" />

* {  margin: 0;  padding: 0;}
body {  display: flex;  justify-content: center;}
.caret-color {  width: 300px;  padding: 10px;  margin-top: 20px;  border-radius: 10px;  border: solid 1px #ffd476;  box-sizing: border-box;  background-color: transparent;  outline: none;  color: #ffd476;  font-size: 14px;  /* Key Style */  caret-color: #ffd476;}
.caret-color::-webkit-input-placeholder {  color: #4f4c5f;  font-size: 14px;}

7.去掉type=”number”末尾的箭头

演示地址：https://codepen.io/qianlong/pen/OJOxLrg

默认情况下，input type = “number”的末尾会出现一个小箭头，但有时我们需要将其去掉。我们应该做什么？

如下图：第二个去掉了，第一个没有。

<input type="number" /><input type="number" class="no-arrow" />

* {  margin: 0;  padding: 0;}
body {  display: flex;  justify-content: center;  align-items: center;  flex-direction: column;}
input {  width: 300px;  padding: 10px;  margin-top: 20px;  border-radius: 10px;  border: solid 1px #ffd476;  box-sizing: border-box;  background-color: transparent;  outline: none;  color: #ffd476;  font-size: 14px;  caret-color: #ffd476;  display: block;}
input::-webkit-input-placeholder {  color: #4f4c5f;  font-size: 14px;}/* Key Style */.no-arrow::-webkit-outer-spin-button,.no-arrow::-webkit-inner-spin-button {  -webkit-appearance: none;}

8.“outline:none”去掉输入状态行

演示地址：https://codepen.io/qianlong/pen/YzErzKG

当输入框被选中时，默认会有一个蓝色的状态行，可以使用 outline: none 去掉。

如下图：第二个输入框去掉了，第一个没有。

<input type="number" /><input type="number" class="no-outline" />

* {  margin: 0;  padding: 0;}
body {  display: flex;  justify-content: center;  align-items: center;  flex-direction: column;}
input {  width: 300px;  padding: 10px;  margin-top: 20px;  border-radius: 10px;  border: solid 1px #ffd476;  box-sizing: border-box;  background-color: transparent;  color: #ffd476;  font-size: 14px;  caret-color: #ffd476;  display: block;}/* Key Style */
.no-outline {  outline: none;}

9.解决iOS滚动条卡住的问题

在苹果手机上，经常会出现滚动时元素卡住的情况。这个时候只有一行CSS会支持弹性滚动。

body,html{  -webkit-overflow-scrolling: touch;}

10.画三角形

演示地址：https://codepen.io/qianlong/pen/rNYGNRe

<div class="box">  <div class="box-inner">    <div class="triangle bottom"></div>    <div class="triangle right"></div>    <div class="triangle top"></div>    <div class="triangle left"></div>  </div></div>

* {  margin: 0;  padding: 0;}
body {  padding: 15px;}
.box {  padding: 15px;  background-color: #f5f6f9;  border-radius: 6px;  display: flex;  align-items: center;  justify-content: center;}
.triangle {  display: inline-block;  margin-right: 10px;  /* Base Style */  border: solid 10px transparent;}/*bottom*/.triangle.bottom {  border-top-color: #0097a7;}/*top*/.triangle.top {  border-bottom-color: #b2ebf2;}/*left*/.triangle.left {  border-right-color: #00bcd4;}/*right*/.triangle.right {  border-left-color: #009688;}

11.画小箭头

演示地址：https://codepen.io/qianlong/pen/ZEaXEEP

<div class="box">  <div class="box-inner">    <div class="arrow bottom"></div>    <div class="arrow top"></div>    <div class="arrow right"></div>    <div class="arrow left"></div>  </div></div>

* {  margin: 0;  padding: 0;}
body {  padding: 15px;}
.box {  padding: 15px;  background-color: #ffffff;  border-radius: 6px;  display: flex;  align-items: center;  justify-content: center;}
.arrow {  display: inline-block;  margin-right: 10px;  width: 0;  height: 0;  /* Base Style */  border: 16px solid;  border-color: transparent #cddc39 transparent transparent;  position: relative;}
.arrow::after {  content: "";  position: absolute;  right: -20px;  top: -16px;  border: 16px solid;  border-color: transparent #fff transparent transparent;}/*bottom*/.arrow.bottom {  transform: rotate(270deg);}/*top*/.arrow.top {  transform: rotate(90deg);}/*left*/.arrow.left {  transform: rotate(180deg);}/*right*/.arrow.right {  transform: rotate(0deg);}

12.图像适合窗口大小

演示地址：https://codepen.io/qianlong/pen/PoOJoPO

vw vs padding

<div class="box">  <div class="img-container">    <img src="https://cdn-images-1.medium.com/max/1600/0*tuDPftoIhupd-qx-.jpg" alt="">  </div></div>
<div class="box">  <div class="img-container">    <img src="https://cdn-images-1.medium.com/max/1600/0*tuDPftoIhupd-qx-.jpg" alt="">  </div></div>
<div class="box-vw">  <div class="img-container">    <img src="https://cdn-images-1.medium.com/max/1600/0*tuDPftoIhupd-qx-.jpg" alt="">  </div></div>

* {  margin: 0;  padding: 0;}
body {  padding: 15px;}
.box,.box-vw {  background-color: #010102;  border-radius: 10px;  overflow: hidden;  margin-bottom: 15px;}
.box:nth-of-type(2) {  width: 260px;}/* vw */.box-vw .img-container {  width: 100vw;  height: 66.620879vw;  padding-bottom: inherit;}/* padding */.img-container {  width: 100%;  height: 0;  /* Aspect ratio of picture*/  padding-bottom: 66.620879%;}
img {  width: 100%;}

13.隐藏滚动条

演示地址：https://codepen.io/qianlong/pen/yLPzLeZ

第一个滚动条可见，第二个隐藏。

这意味着容器可以滚动，但是滚动条是隐藏的，就好像它是透明的一样。

<div class="box">  <div>    I'm fatfish, 6 years of programming experience, like front-end, writing    and making friends, looking forward to becoming good friends with you.  </div></div><div class="box box-hide-scrollbar">  <div>    I'm fatfish, 6 years of programming experience, like front-end, writing    and making friends, looking forward to becoming good friends with you.  </div></div>

* {  margin: 0;  padding: 0;}
body {  padding: 15px;  color: #324b64;}
.box {  width: 375px;  overflow: scroll;}/* Key Style */.box-hide-scrollbar::-webkit-scrollbar {  display: none; /* Chrome Safari */}
.box > div {  margin-bottom: 15px;  padding: 10px;  background-color: #f5f6f9;  border-radius: 6px;  font-size: 12px;  width: 750px;}

14.自定义选中的文字样式

演示地址：https://codepen.io/qianlong/pen/jOaGOVQ

<div class="box">  <p class="box-default">    I'm fatfish, 6 years of programming experience, like front-end, writing    and making friends, looking forward to becoming good friends with you.  </p>  <p class="box-custom">    I'm fatfish, 6 years of programming experience, like front-end, writing    and making friends, looking forward to becoming good friends with you.  </p></div>

* {  margin: 0;  padding: 0;}
body {  padding: 15px;  color: #324b64;}
.box > p {  padding: 10px;  background-color: #f5f6f9;  border-radius: 6px;  font-size: 12px;
  margin-bottom: 15px;}/* Key Style */.box-custom::selection {  color: #ffffff;  background-color: #ff4c9f;}

15.不允许选择文本

演示地址：https://codepen.io/qianlong/pen/rNYGNyB

第一个内容可以选，第二个不可以选中了。

<div class="box">  <p> I'm fatfish, 6 years of programming experience, like front-end, writing    and making friends, looking forward to becoming good friends with you.</p>  <p> I'm fatfish, 6 years of programming experience, like front-end, writing    and making friends, looking forward to becoming good friends with you.</p></div>

* {  margin: 0;  padding: 0;}
body {  padding: 15px;  color: #324b64;}
.box p {  margin-bottom: 15px;  padding: 10px;  background-color: #f5f6f9;  border-radius: 6px;  font-size: 12px;}/* Key Style */.box p:last-child {  user-select: none;}

16. 水平和垂直居中元素

演示地址：https://codepen.io/qianlong/pen/VwrMwWb

<div class="parent">  <p class="child">I'm fatfish, 6 years of programming experience, like front-end, writing    and making friends, looking forward to becoming good friends with you.</p></div>

* {  margin: 0;  padding: 0;}
body {  padding: 15px;  color: #324b64;}
.parent {  padding: 0 10px;  background-color: #f5f6f9;  height: 100px;  border-radius: 6px;  font-size: 12px;  /* Key Style */  display: flex;  align-items: center;  justify-content: center;}

17.单行文字溢出时显示省略号

演示地址：https://codepen.io/qianlong/pen/vYWeYJJ

<div class="box">  <p class="one-line-ellipsis">Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish,Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish</p></div>

* {  margin: 0;  padding: 0;}
body {  padding: 15px;  color: #324b64;}
.box {  padding: 10px;  background-color: #f5f6f9;  border-radius: 6px;  font-size: 12px;}
.one-line-ellipsis {  /* Key Style */  overflow: hidden;  white-space: nowrap;  text-overflow: ellipsis;  max-width: 375px;}

18.多行文字溢出时显示省略号

演示地址：https://codepen.io/qianlong/pen/ZEaXEJg

<div class="box">  <p class="more-line-ellipsis">Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish,Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish</p></div>

* {  margin: 0;  padding: 0;}
body {  padding: 15px;  color: #324b64;}
.box {  max-width: 375px;  padding: 10px;  background-color: #f5f6f9;  border-radius: 6px;  font-size: 13px;}
.more-line-ellipsis {  overflow: hidden;  text-overflow: ellipsis;
  display: -webkit-box;  /* set n lines, including 1 */  -webkit-line-clamp: 2;  -webkit-box-orient: vertical;}

19.清除浮动

演示地址：https://codepen.io/qianlong/pen/dyZVyZW

这是一种老式的布局方式，现在大部分移动端都不用了。

如下图，外层的高度没有塌陷，这就是为什么要使用clearfix类。

<div class="box">  <p class="more-line-ellipsis">Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish,Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish, Hello Fatfish</p></div>

* {  margin: 0;  padding: 0;}
body {  padding: 15px;  color: #324b64;}
.box {  max-width: 375px;  padding: 10px;  background-color: #f5f6f9;  border-radius: 6px;  font-size: 13px;}
.more-line-ellipsis {  overflow: hidden;  text-overflow: ellipsis;
  display: -webkit-box;  /* set n lines, including 1 */  -webkit-line-clamp: 2;  -webkit-box-orient: vertical;}